Abstract: Taking the two maize varieties Zhengdan 958 and Fengdan 3 grown on the three accumulated temperature zones (Ⅰ，Ⅱ and Ⅲ) in Heilongjiang Province as test materials, a field investigation was made in 2010 and 2011 to study the effects of PASPKTNAA (PKN), a compound of exogenous plant growth regulators, on the grain filling and yield of the varieties under different environmental temperatures. From  zone Ⅰ to  Ⅲ, the air temperature at the grain filling stage had a decreasing trend, with the average minimum temperature being 12.16, 11.40, and 9.56 ℃, respectively. The effective accumulated temperature at the midlate stage of grain filling was too low to be sufficient for grain filling, which severely affected the grain filling process. Applying N, P and K promoted the dry matter accumulation of maize grain and the grain filling rate in the  three zones, delayed the peak time (T_max) of the grain filling rate of Fengdan 3 but advanced that of Zhengdan 958， promoted the growth capacity at peak time of grain filling rate and the maximum grain filling rate of the two varieties, and shortened their active grain filling period. Applying N, P, and K increased the grain yield of the two varieties in the three zones obviously, and, as compared with those in zones Ⅰ and Ⅱ, the grain yields of Zhengdan 958 and Fengdan 3 in zone Ⅲ were increased by 8.2% and 5.1%, and 3.4% and 0.8%, respectively. Therefore, applying N, P and K could help maize utilizing the limited accumulation temperature, improve the grain filling rate, decrease the grain water content, and ultimately, increase the maize yield.