Abstract: An experiment was conducted to measure the soil moisture,soil temperature,leaf's area,leaf's numbers,degradable states of films and yield of corn in the field covered by three kinds degradable films and one kind of ordinary film.The results indicate that the degradable films have the remarkable function of heat and humidity preservation in the pre-growing period of corn.And the leaf's area increases evidently though the leaf number does not change significantly.The liquid degradable film owns the quickest degradation without environmental pollution,and can be applied on the crop which has short growing period,such as vegetables.The biological degradable film decomposes slowly and shows an effective environmental protection function with a higher yield of corn than that of bare ground,so it can be used in the crop which has a long growing period.The bio-photo degradable film decomposing most slowly can increase the yield evidently though its environmental protection function is not evident,so it is suitable to the crop which has a long procreation age.