Under the situation of growing water shortage, determining the optimum irrigation period and the best irrigation quantity of winter wheat is an important issue that needs immediate solution in Baoding, Hebei Province. In order to determine the optimal irrigation quantity and irrigation time, this paper using WOFOST model to simulate the winter wheat in Baoding Area. In this paper the Baoding Station is selected as a representative station. During the different rainfall year types in 2003/2004, 2005/2006 and 2008/2009, the different irrigation plans and quantities are simulated, including irrigating once, twice and three times, to reveal the correlation between the yield under water stress and irrigation time. The simulation results show that optimal irrigation time in the whole winter wheat growth process is the period of booting stage and heading to filling stage. During these periods, irrigation can achieve the most obvious effect, and have the highest contribution to wheat yield. Besides, the best plan of irrigating twice and three times to meet the winter wheat growth is given out, which might help obtain greater economic benefits at the same time.