To research the crop potential productivity can find the obstacle to improve yield, and can offer grounds for programming agricultural production. The temperature and climate potential productivity of Changwu experimental district in many years are compared with practical yield of winter wheat and spring maize. The results show that the wheat average heat potential productivity of the district in many years is 6910.5 kg/hm², that of maize 10718.6 kg/hm², the variance between years is not big. The wheat average climate potential productivity is 6190.3 kg/hm², that of maize is 8768.7 kg/hm²; variance between years very large in 1986-1990, the realizing rate is comparative low, but in 1990-1994, the rate is very high, almost equal to the climate potential productivity of the district. The items that are important in the future are: to stable chemical fertilizer application and rational proportion between N and P; to universe use of film mulches and stubble mulches; to increase the mount of organic fertilizer and the efficiency of field managements.