Abstract: In order to explore the yield increasing mechanism of different plastic film mulching modes, and improve the maize mulch techniques, leaf area index, accumulation amount of dry matter, yield and its components were compared between the two maize planting methods, covering film between rows （CBR） and covering film on rows （COR）, using no covering film （CK） as control. The results showed that technological effects of COR was the highest, followed by this of CBR and CK. Growth period of COR was 4-6 days earlier than other methods. Ear length, hundred-grain weight and kernel rate were increased and bare tip length was decreased by covering films. Yield and the tested indexes of COR was better than these of CBR and CK.