The effects of terrestical pollution on zooplankton are analyzed for the Bohai Bay and the estuary areas of rivers along Tanggu coast (1979-1980). The main results are as follows: 1. There are no distinct effects observed on marine zooplankton in the offshore waters of the Bohai Bay. And the marine zooplanktion maintains a normal ecological balance. 2. The animal plankton distribution in the nearshore areas close to the mouths of rivers shows some abnormal phenomena in its species composition and quantitative distribution. 3. The pollution has harmed the organisms and reduced them in both species and number of individuals within the debouchments of the rivers. It is clear that the contents of heavy metals and organic materials in the samples of water, surface sediments and planktonic organisms are decreased with the seaward flowing of polluted water, So the estuary process has played an important role in purification of the waters. According to the ecological features of the zooplankton, the area investigated covering the estuaries to the sea may be classified into four different zones: (1) heavily polluted zone；(2) slightly polluted zone; (3) trace pollution zone and (4) purified zone.