Taking spring maize varieties (Zhenghong 6, Zhongyu 3, Xianyu 1171 and Chengdan 30) popularized in large area in Sichuan Province as materials, the dynamic change rules of stalk lodging rate, moisture content, dry weight and mechanical strength under ear after physiological maturity were studied in order to clarify the main influencing factors of stalk lodging under ear after physiological maturity of spring maize. The results showed that the rate of stalk lodging under ear increased after physiological maturity of spring maize in Sichuan province. Zhenghong 6, Zhongyu 3, Xianyu 1171 and Chengdan 30 could meet the requirement of lodging machine harvest before 2.6, 17.9, 14.6 and 19.3 days after physiological maturity, respectively. The moisture content, dry weight and mechanical strength of stalk under ear decreased after physiological maturity, and there were significant differences among maize varieties. Stalk lodging rate under ear was negatively correlated with moisture content, dry weight and mechanical strength of stalk under ear, but positively correlated with moisture content, dry weight and mechanical strength of stalk under ear. The moisture content, dry weight, rind penetration strength of the third segment, bending strength of the third segment and the stalk lodging rate under ear all accorded with the exponential function, and the fitted equation F test has reached a very significant level.