Through correlation analysis to rainfall and wheat yield in Shaanxi province,an opti-mum regression model of them is established.It is indicated that in the north of Yanan,the westand east of rairifed highland in Guanzhong plain and along the north slop line of the Qinlingmountains,the yield-increasing of rainfall is not normally brought into play,but in the middlepart of Guanzhong plain and the south of Yanan,this effect brings into play to a certain extent.And the corresponding yield-increasing measures for wheat in various areas of this province areput forward.