Abstract: In order to clarify the function of soil conditioner on improving soil physical and chemical characteristics and increasing crop yield and determine the best application rate to extend in agricultural production, the author took Fangshan District of Beijing as an example to study the effect of applying soil conditioner on soil properties and crop production in facility vegetable fields. The results showed that: the application of soil conditioner on the facilities field would improve apparently the soil field capacity, soil cation exchange capacity (CEC) and the yield of tomato, the relationship between the amount of soil conditioner and the soil field capacity, soil cation exchange capacity (CEC) and tomato yield could be fitted with the equations of y=-8×10- 5x2 0.0329x 27.34 (R2=0.958), y=-0.0004x2 0.0639x 16.39 (R2=0.9344) and y=-0.0041x2 0.5155x 77.725 (R2=0.9877). Therefore, the best application amount of soil conditioner was 60-75 L/hm2.