Abstract: Based on the analysis to the influence disciplinarian of poplar shelter forest belts on the output of wheat,the paper shows that the wheat output nearby the shelter forest belts are changed much because of the belt influence.There exist reduction area,increasing area and normal area of wheat output from shelter forest belts to the farmland.In the range from the belt to 0.4 H,the wheat output is decreased.And the output is the same as comparison area in the range from 0.4 H to 0.7 H.But the output is increased greatly in the range from 0.7 H to the farmland.The outputs of wheat at south and east sides of shelter forest belts are influenced lightly,but they are strongly at north and west sides.Among the influent factors,the projection area of tree crown has a great affect on wheat output.The coverage of crown can restrain the wheat output obviously.Root system cutting measures can protect the tree roots growing into farmland.The negativeeffect of shelter forest belts on wheat output can be decreased efficiently.