Studies on plant density of maize were carried out in 2007 and 2008 on the long-term protective maize cultivation field in the Xiangshan village of Gongzhuling city,Jilin Province.The relationship between plant density and yield in wide/narrow row alternation was studied and this cultivation method was compared with traditional planting.The optimum density of wide/narrow row alternation cultivation in the middle of Jilin Province were made clear.