Based on the history materials of Calanus sinicus in Taiwan Strait and its Adjacent sea areas, the distribution and reproduction of C.sinicus were researched. The results show that C.sinicus distributed all year round, in north and middle parts of Taiwan Strait, but seasonally in south part of Taiwan Strait and Xiamen Harbour. The number of C.sinicus in these regions attainted its great maximum in spring. Secondary maximum in winter, and minimum in autumn even disappeared. The abundance of C.sinicus is more near shore than off shore, more in the north than in the south in horizontal distribution. C.sinicus distribute from bottom layers to surface layers, but its adults live in bottom layers in summer and in upper layers up 35m in winter. Diurnal vertical migration of C.sinicus is marked. There were three main breeding period (i.e. 3 generations) in Taiwan Strait and Xiamen harbour. The relative questions were discussed in this paper.