Abstract: Effects of the coupling of straw(wheat)-return and different nitrogen amount (four levels)on photosynthetic characters and yield of wheat were studied under field condition.The results show that straw-return can improve photosynthesis of wheat,gets higher thousand-grain weight and grain yield compared to the normal(non-straw) cultivation.The rates of photosynthesis and transpiration of wheat of straw-return treatments are enhanced with the increasing of N fertilizer to a certain applied level.But they start to decrease when the nitrogen is applied more than 225kg/hm².The coupling of straw-return and N fertilizer application can increase the wheat yield mainly through affecting the number of ears per hectare.The optimal amount of N fertilizer applied to wheat with straw-return is 225kg/hm².