Abstract: The research aimed to master the optimum planting density of the Maize variety ‘Qiaoyu 8’ which suitable for summer maize mechanized harvest in Henan province, the single-factor randomized trial was designed in this study, analyzed the effects on the leaf area index, the lodging rate, the lodging resistance, the mechanized harvest indicators and the yield in different density treatments. The results showed that the leaf area index increased first and then decreased in the whole growth period, and reached the peak value in the tassel period. With the increase of planting density, the lodging rates increased, stem diameter of the 3rd internode above ground was thinner and the rind penetration strength of the 3rd internode above ground decreased, the grain loss rate and grain crushing rate were increased too, while the impurity had no obvious change. From analyzing the production, grain moisture content, lodging rate, mechanized harvest indicators, the suitable density of ‘Qiaoyu 8’ should be 8.25-9.00×104 plants hm-2.The results would provide reference for reasonable planting density and good quality mechanized harvesting for high-yield cultivation of maize varieties.