Fish productivity characteristics of 36 representative large- andmiddle-sized reservoirs in Shandong Province were investigated in 1989 and 1990.17 items concerning characters of the drainage areas, morphological, hydrolo-gical, hydrochemical and biological features, and the status of reservoir fisherywere completely included in the investigation. On the basis of these results, fishproductivity of the reservoirs was assessed with systematic cluster analysis,ranking method and regression analysis. In assessing with the ranking method a systematic approach was followed toclassify the reservoirs into five ranks, and on the basis of the average fish produc-tion of 2 well--managed typical reservoirs over a number of successive years andin accordance with the average plankton abundance of the reservoirs in each rankthe fish productivity of each rank was estimated to be 440, 370, 290, 220 and150 kg.ha~(-1) respectively. From the results of regression analysis it was shownthat the major factors affecting the levels of reservoir fish produotivity were:the soil fertility, the density of population and the rate of vegetation cover withinthe drainage area; and the total phosphorus, the total nitrogen, the electric conduc-tivity, the chemical oxygen demand and the plankton abundance of the reservoirwater. Among all of them soil fertility was the strongest one.