Abstract: In order to grasp the laws of ecological climatic factors on seed weight of winter wheat in dryland of the middle loess plateau, scientifically develop and utilize the climate resources, improve the productivity benefits of winter wheat. Based on experiment data at agro-meteorological experiment station of Xifeng, Gansu Province and meteorological data from 1995 to 2009, the relationship between TKW of wheat and grouting rate, spacing interval had been analyzed with statistics methods. The author found the characteristic of impact of synthetic eco-climatic factors on TKW. The result showed that the contribution rate of grouting rate for TKW was 69% and 2.23 times of that grouting spacing interval. It showed increasing trend of TKW and sprouting rate year by year indicated that variation of eco-climatic factors were still restricts to the suitable option. There still was range of increasing potential of yield per unit. It also showed that the when the precipitation increased by 10 mm during the pustulation period, the TKW would be increased by 2.15 g , The active accumulated temperature increased by 100℃, the TKW would be decreased by 2.7 g The relative air humidity increased by 1%, the TKW would be decreased by 1.0 g.