In this papery the following eigenvalues of fish communities were caleulated: the number of species contained in. communities; the index of eonrentrar tion;the index of species richness; the maximum species diversity;the index of evenness and the index of degree of overlap. Their regional, monthly and yearly changes were analysed The results indicated that the structure of fish communities of outer waters (10 to 35 meters in depth) is mare complicated than that of inner waters (7 to 10 meters in depth)，The changes of species diversity have some relation to the dominant species and fishing efforts. In the calculation of species diversity both numbers and biomass were considered.