Robert Hart was the founder of the modern Chinese Maritime Customs and had a great influence upon the Ch'ing Dynasty's foreign policy decision-making process. In 1870's,France began her military colonization toward the Vietnam which country at then was under the Ch ' ing's suzerainty. French advance had created a severe conflict with China. The Conflict between China and France escalated in the 1880’s; a lot of Chinese high rank officials urged the government to take a hard line attitude toward the French adventure in Vietnam. At that time, Hart knew that the Chinese did not want a war with France, but he also had observed that the Chinese senior officials wanted to save their face and this situation forced them to take the hard-line position. The domestic power struggle between the Chinese senior officials made the peace negotiation, Li Hung-chang (李鴻章) as the representative of China and Frederic Bouree of French, a tragedy. The French new Prime Minister Jules Ferry was not satisfied with the outcome of the Li-Bouree peace agreement and Bouree was dismissed. Chinese government took Ferry's action as a signal of war and ordered the Chinese forces advanced into Vietnam. The Tsungli Yamen (總理衙門) also did not give Mr. Li the full power to negotiate with the French special envoy Arthur Tricou. The Chinese Army who disguised as the Black Flags Army, a rebel force stationed in Tongking and leads by Liu Yung-fu (劉永福) , made a secret war with the France Army. The French Navy captain Francois-Ernest Fournier made a personnel contact in Hong Kong with Gustav Detring, German commissioner of Chinese Maritime Customs who was on his way to Canton ,and proposed to take a peace negotiation between the France and China. The Tsungli Yamen order Mr. Li to negotiate with Fournier and Detring played a very important role in this negotiation. On May 10, 1884, Li and Fournier signed the T'tsin Convention. Hart was very unpleasant with .the Li-Fouriner peace-agreement not only Mr. Li gave the French a Carte Blanch, in his point of view, but also because. Germany had a superior influence upon Chinese foreign affairs policy-making process than him, an Englishman. According to the Li-Foumier agreement, The Chinese must withdraw within twenty days all her troops from Tongking (東京，北圻) but the Ch'ing government knew nothing from Mr. Li. and finally the clash blew out again in Tongking. The T'tsing Convention was torn down. The Ch'ing Dynastysent Tseng kuo-ch'uan (曾國荃) made a peace talk with the French envoy Jules Patmotre in Shanghai and Hurt had participated in this negotiation. In Hart's point view, the Chinese must accepted the T'tsing Convention before she got great damage in the war with France. The Tsungli Yamen thought that Hart's idea had not any bad intention but his coward shall disturb Chinese attitude towed the France. Hart was forced to return to Peking. In this time, the French held a very hard-line attitude. In spite of forcing the Chinese to paya lot of money, they also wanted to get the Keelung, Taiwan. The France Navy attacked Foochow, the Chinese South Fleet naval base, destroyed the South Fleet and then blocked Taiwan. The Chinese asked the United States, Garman and England as a peace mediator but got a very cool response. Hart urged the Chinese to accept the T'tsing Convention otherwise the French shall take Taiwan and this would be a big shock to Chinese. The Chinese government did not retreat just because it shall lose their face, but their attitude began soften. At this time, Hart wrote to James Duncan Campbell, the representative of the Chinese Maritime Customs in England, and suggested that it was their show time to make a peace settlement. Under Hart's mind, there were two guide-lines, the first was that they must avoid the blood-shed and tragedy, the second was that the English influence shall not be excluded from China. A Chinese Maritime Customs ship Fai-Hoo (飛虎號)was arrested in October 1884 by the French Navy. Hart thought it would be a good chance for Campbell to make adirect contact with Furry. On January 17, 1885, Campbell met with Furry and implied that Hart was full authorized by the Ch'ing Dynasty Court to make a peace settlement with France. Ferry wanted to cease the war with China but he was also in deep cautions in dealing with the secret negotiation between himself and Hart. In this period, Mr. Li did not have any idea of this peace talk nor the foreign Legations in Peking. Although the Chinese Army defeated the French Army and recaptured Lang-son (諒山) , this incident did not stop the peace process. On April 4, 1885, Campbell and Albert Billot. Head of the political affairs section in the French Foreign Ministry, signed the peace agreement and the ceasefire between the Chinese and French Army was come into force immediately. Obviously, the silences of the Chinese hard-line officials indicated that Hart got not only fully support from the Prince Ch'un (醇親王) but also from the Empress Dowager Tz'-hsi (慈禧太后) herself. Mr. Li did not play a very important role in the final stage of peace-making process with the France. The Peace agreement that ended the Sino-French Conflict in Vietnam was a good example of Hart’s impressive influence upon the Ch ' ing's foreign relations decision-making process.