The present paper deals with secular analysis of zooplankton biomass in the eastern area of the Yellow Sea during the last seven years from 1963 to 1969. The annual variation of zooplankton biomass in the research area shows increase since October 1965, the lowest point. The increasing shape is a parabola expression, BM= 0.0146 $T^2+0.0448T+38.0436$ (BM, Biomass; T, Time, of which zero point is placed at December 1965).