Objectives of the study were to know the photosynthetic reaction mechanism of corn leaves under dif-ferent plant density with different temperatures in semiarid area, in order to promote reasonable utilization of the lo-cal light and heat resources and to dig deeper production potential of spring maize. Effect of temperature change onphotosynthetic factors of corn under different density, and the variation trend of net photosynthetic rate under differ-ent temperatures during the grouting process in Taonan area of Jilin Province were determined. The results showedthat there were nearly no significant differences in Pn under each planting density of ZD958, XY335 and NH101 at 22~30℃, significant or very significant differences occurred in the high density population. The Pn increased grad-ually at 22~26℃ and it changed little at 26~28℃ when it reached high value, but it decreased significantly at 28~30℃. Tl, Tr, Gs and Ci of plants increased gradually as the environmental temperature gradually increased,and the Pn of leaves significantly increased too. Although increasing planting density could decrease photosyntheticcapacity for single-plant, and organic substances synthesis been limited, but the total dry matter accumulation andyields increased in high-density population. To extend the grain filling duration when the ambient temperature at 24~28℃ by rational adjustment of cultivation and management measures could extend high Pn duration of popula-tion in the filling process. It was the most effective method to improve utilization of light and temperature resourcesand increase the yield.