Abstract: In order to clarify the suitable sowing date of summer maize in the rape-summer maize cropping system of Sichuan Basin, three maize varieties(Zhongyu 3, Liyu 16 and Chengdan 30)were sowed at four dates with 15-day intervals from May 1st to June 14th in 2016, and the effects of different sowing dates on the actual lodging, dry matter accumulation, grain yield and grain quality were investigated. The results showed that maize varieties, sowing dates and their interactions had significant effects on root lodging percentage, total lodging percentage, harvest index, grain yield and ear number, and the effect of sowing dates was greater than that of maize varieties. The starch content of maize grain was significantly affected by varieties, but protein content was significantly affected by both of varieties and sowing dates, and the effect of maize varieties on content of starch and protein was bigger than that of sowing dates. Timely early sowing of summer maize had good effects on lodging-resistant capability, harvest index and grain yield. Consideration of high yield and good grain quality of summer maize, and the variety of ‘Chengdan 30’was appropriate for sowing from May 1st to May 15th, while the preferred variety should be ‘Zhongyu 3’ or ‘Liyu 16’ for delayed sowing maize after May 15th in hilly regions of Sichuan.