Abstract: Macrobenthic species diversity in southern and central Bohai Sea was studied on the basis of quantitative investigations of macrobenthic abundance and biomass as well as secondary production in three cruises carried out in June 1997, September 1998 and April 1999. The results show that there is no obvious trend in planar distribution of macrobenthic species diversity within the surveyed areas. Statistical analysis demonstrate that diversity indices have closer relationships to sediment factors than to bottom water factors, and sediment pollutant contents have negative effects on macrobenthic species diversity. Variation of Shannon Wiener index in three seasons was not significant ( P >0.05) when comparing the averages of samples from the same three stations among the three cruises. Moreover, there is no marked difference in the average Shannon Wiener indices from 20 common stations between cruises in September 1998 and April 1999 ( P >0.05). The species number in the Bohai Sea is higher than in Jiao Zhou Bay, China.