In order to clarify the effect of nitrogen application rate on the lodging resistance of densely planted maize stalks under the conditions of water and fertilizer integration and nitrogen fertilizer application, in 2019, nine nitrogen fertilizer levels were set up in Qitai, Xinjiang and Tongliao, Inner Mongolia to investigate the maize stalk breaking resistance, plant morphology, basal internode puncture strength and dry matter accumulation under different nitrogen application rates, and establish the relationship between nitrogen application rate and these indicators. The results showed that in a certain range of nitrogen application, with the increase of nitrogen application, the resistance to break, RPS and DWUL of maize stalk increased gradually. When nitrogen application reached a certain amount, the resistance to break, RPS and DWUL of maize stalk basal internode did not increase. The plant height, ear position height and ear position coefficient also increased with the increase of nitrogen application. Correlation analysis showed that the stem breaking resistance was negatively correlated with plant height, ear height and ear coefficient, and positively correlated with RPS and DWUL of basal internode. The results show that under the condition of water and fertilizer integration and nitrogen fertilizer application, increasing nitrogen application can improve the mechanical strength and the lodging resistance of maize stalk by increasing the dry matter accumulation in maize stalk.