Most previous studies of the decline of An-ping Harbor have been textual analyses that often lack substantiating statistics. It is generally agreed that import and export figures are the most significant elements in examining the shipping capacity of a harbor. Hence, this essay attempts to clarify the vicissitudes of trading activities in An-ping Harbor during Japanese rule by using statistics taken from Taiwan (Formosa) Annual Statistic Report of Foreign Trades and Taiwan (Formosa) Annual Statistic Report of Trade compiled by the Taiwan Governor-General's Office. It will also elucidate the trade characteristics of An-ping harbor. The study focuses on three aspects: importation, exported goods, and imported goods. Its findings are as follows: 1. The overall trade through An-ping Harbor during Japanese rule experienced positive growth, contrary to the general belief that the harbor was in decline. However, after 1906, the direction of trade reversed, with imports exceeding exports, and An-ping Harbor became a typical importation harbor. 2. In terms of trading markets, after 1905, both importation and exportation through An-ping were directed toward the Japanese mainland, as demonstrated by the fact that Taiwan’s trade with Japan far exceeded its trade with other countries. 3. As the decline of sugar and rice exports slowed the growth of the An-ping Harbor, textile and paper imports became the basis of the harbor's trade. The total amount of imports of these two goods far exceeded that of the Kaohsiung Harbor during this period.