With the aim of reducing agricultural pollution caused by plastic films，the degradation properties of degradable films and their effects on growth and water use efficiency of maize are studied with results compared with the effects of plastic film in an open － field experiment in Hexi Irrigation area． The results show that: compared with the results of open－field experiment，the coverage of degradable membranes A，B，and C can significantly increase the number of root layers，root number and root dry weight in seedling and jointing stages． The plant height，leaf area and dry matter accumulation increased significantly during different growth stages． The number of grains per ear increases by 20．25% ～ 20． 79%，the 1000 －grain weight increases by 14． 44% ～ 21． 69%，and the yield increases by 37． 88% ～ 47． 01%． Degradable film does not show significant difference with plastic film． Compared with plastic film，the economic output and the water use efficiency of dry matter increases by 3．66% and 1．68% for test film A，while those of the test films B and C decreases by only 6．50% ～ 7．08% and 6．38% ～ 7．17%． However，from grain filling stage to maturity stage，the water consumption of test films B and C increases by 7．21% and 12．86%，while the water use efficiency of dry matter decreases by 15．31% and 12．61%，which indicates that the effect of degradable film on soil moisture conservation decreases sharply in the later stage of film mulching． The results show that it is feasible to use degradable plastic film instead of plastic film in agricultural production． It is suggested that the production enterprises should prolong the stable period of test films B and C to improve the effect of moisture conservation in the later stage of maize growth．