Forty seven years have passed since 1949, the year that the K.M.T. (the then ruling political party in Mainland China and current ruling party in Taiwan) government moved to Taiwan. When we look behind, during this past forty some years, we have found that the relationship between Taiwan and Mainland China actually has undergone the periods of military conflicts and cold war tensions. It was not until 1987, with the growing trends of democracy in both politics and society in Taiwan plus the fast changes of the situation between both hsides of the Taiwan Strait, that on November 2, 1987 the Govemment of the Republic of China declared the release of the long-term ban on its citizens' going to Mainland China for relastive visiting while at the same time, the China Communist's regime also loosened part of its regulations and administrations in this regard; thus the long-term segregation and tension was broken, impelling the exchanges and communications in the civilian level for both sides of the Tiawan Strait regarding social, cultural, educational, jurispurdent, economic and trading fields, and pushing the relationship between both sides into a new era "Civilian communication period". Due to the fact that currently the contacts between both sides have become more and more frequent and the trade disputes plus the judicial problems have gained their way, we have to actively understand and study the judicial system formulated under the longterm, effective rule by the Chinese Communists in Mainland China, Which is the very motive of the study for this thesis. Based on the present judicial system in Mainland China, there are, basically four branches in the contents of its judicial rights, namely the right of trial, the right of investigation, the right of inspection and the right of judicial administration. According to the relevant statutes in the Chinese Communists' Constitution and laws, the People's Court is the national trial institute and thus administers the right of trial for the nation; the People's Investigation Bureau is the supervising institute for the national laws, and thus administers the right of investigation for the nation, the Public Security and the National Security Institutes are the agencies for national security and protection, and thus administer the right of inspection for the nation; the Judicial Administrative Institute is in charge of the judicial affairs concerning prisons, labor reformations, public notaries, and lawyers, and thus administers the right of judicial administration for the nation. Each individual judicial branch is responsible for its own tasks, yet it has to correspond with and be bond by one another, and thus forms a compact and close judicial system. This thesis, except for its preface, first made a complete description based on the judicial organizational structure under the forty years' separation between both sides; secondly discussed the differences of the court systems, the investigation systems and the public security (inspection) systems respectively between both sides, in order to understand the practical operations of the judicial institutes on both sides. Finally, it made further analysis and comparison of the loss and gain in the judicial systems on both sides, so as to extract the forte from both sides, to reform jurisdiction and to provide a suitable solution when citizens from both sides come to disputes, which is the key point we should work hard for.