This research,based on the observational data of climate and agrometeorology from 1981 to 2010 of Tongwei meteorological observation station in Gansu Province,conducted primary research toward the influence of climate change and cultivars change on the winter wheat in semi-arid region of Loess Plateau through correlation analysis, trend analysis,variance analysis and other methods. The results showed that the district has warming and drying trend that the temperature increased (increase rate: 0.225℃·10a ~(- 1)) and the precipitation decreased (decrease rate: 23.879 mm·10a ~(- 1)) in the past 30 years. The reduction of precipitation and cultivars shift led to the shortening of winter wheat growth period. In the past 30 years,the winter wheat yield of Tongwei County in Gansu has increased by 4 514.97 kg·hm ~(- 2),temperature increase and precipitation decrease during its duration period have no obvious effect on the increase of winter wheat yield (facilitation influence). The cultivars shift toward winter wheat can increase the yield at a range of 8.8% ~ 132.0% and the variable coefficient was within 4.1% ~ 65.6%. The variance analysis showed that the average yield of different cultivars have significant difference (F = 4.056,P < 0.01). It can be found that the cultivars shift led to a significant increase of winter wheat yield through analyzing the yield changes of different years,climate and cultivars.