Abstract: The effect of propamidine on plant growth,chlorophyl content,photosynthetic parameters and the prophase yield of tomato (Lycopersicon esculentum Mill.) was investigated. The result showed that propamidine could promote the seedling growth,and the effect was related to the dose of propamidine. At high dosage(100.00 g/hm2),propamidine lowered the relative growth rate of tomato height by 35.00% and enhanced the net increase rate of stem diameter by 151.96%, compared with the control.After treatment of propamidine,the content of chlorophyl a,chlorophyl a+b and carotenoid were increased by 22.02%,15.17% and 13.04%,respectively.And the net photosynthetic(Pn),stomatal conductance(Gs) and transpiration(Tr) were increased by 21.80%,42.31% and 53.72%,respectively.However,the intercellular CO2 concentration(Ci) was lowered by 9.58%.At the same time,the thickness of tomato leaves was increased by 21.88%,but the weight of unit area of tomato leaves was reduced by 13.95%.All factors mentioned above lead to output increasing of tomato by 25.70%. The result suggested that,under recommendatory dosage,propamidine could promote the seedling growth and increase the prophase yield of tomato.