It has been in dispute for a long time whether the Jiande Group and its related strata in Zhe-jiang, Fujian and Jiangxi Provinces, southeastern China, should be assigned to the Upper Juras-sic or Late Cretaceous. Such disputes also exist concerning the continental Jurassic-Cretaceous boundary in different parts of China. Recently, studies of marine fossils in eastern Heilongjiang have resulted in some breakthroughs in the problem. In 1970's, the Jurassic-Cretaceous bound-ary in eastern Heilongjiang was placed at the top boundary of the Jixi Group and Longzhaogou Group in the Stratigraphical Table of Heilongjiang Province. However, at present, fossils in ma-rine interbeds have revealed that the major beds containing coal in the two groups mentioned above basically belong to the Lower Cretaceous System. Correlation between eastern Heilongjiang and its related parts of China shows that the upper part of the Rehe Group, western Liaoning, and the upper part of the Jiande Group, western Zhejiang Province, should belong to the Lower Cretaceous System rather than the Upper Jurassic System.Now that the Shouchang Formation in the upper part of the Jiande Group belongs to the Lower Cretaceous, where should the Jurassic-Cretaceous boundary be set? Owing to shortage of fossils in the Huangjian Formation and Laocun Formation below the Shouchang Formation, western Zhejiang, it is difficult to solve the problem by the biostratigraphical method. Fortunate-ly, correlation carried out through many advanced methods by different institutions and a lot of reliable isotopic age data obtained in these areas make it possible to solve the problem. Based on the data from some representative areas in the three provinces, this paper reveals that the Jiande Group and its related strata mainly belong to the Lower Cretaceous, and only in the west part of the region, do some strata belong to the Upper Jurassic.