Abstract: In this paper a method of computing spatial and temporal average radar's equivalant reflection factors Ž, is suggested. The effect of 75 randomized precipitation enhancing exp0riments (1982-1984) in Fujian Gutian River Basin with the method is analysed. The result of 37 seeding experiments indicafes that the average relative increment is 20.34% and absolute increment is 26.5(mm6/m3).The effectiveness of Že has been confirmed as compared with the regression analysis of precipitation. An increase in Že indicates that the bigger drop's number density in cloud may be increased by seeding.