Abstract: In order to explore the changes of growth and its yield components of spring wheat at different sowing dates by using whole-field plastic (i.e．,the whole soil surface in a field is first mulched with plastic,on top of which a soil layer about 1 cm thick is spread) , taking Dinxi40 varieties was conducted.The emergence of each growing period 、biomass 、yield components were observed．Results showed that the sowing date had a significant effect on the development of spring wheat,With the delay of sowing date, the whole growth period was shortened obviously,the whole growth period of late sowing spring wheat is shortened about 5 days that of the early ones. With the delay of sowing date, the time of vegetative growth of spring wheat was shortened. But its reproductive growth time showed a prolonged trend. the occurrence time of maximum accumulation rate of dry matter per plant was advanced.The maximum growth rate of dry matter increased, the number of spikelets of late sowing spring wheat is significantly higher than the early sowing ones.In the whole growth period,the soil moisture content of the late sowing spring wheat was higher than that of the early sowing spring wheat.It shower that in the semi-arid region of the Loess Plaeau,it is better to postpone the sowing date of wheat to increase the yield.