Based on the results of field experiment and the meteorological data by predecessors, using Penman's formula and the theory and method of potential productivity of climate, the evaluation on the water condition of winter wheat in Cangzhou egion is analysed. The productive efficency of irrigated water in different period is investigated in theory. The results show that the water condition is better beforewin-ter, yet water supply after the reviving is out of proportion to water requirement, . an amount of water deficit is about 88-138mm in each growing period, the yield decreased about 18-50%The effect of irrigating on the increased yield is the best at jointing-earing stage under the same irrigated quantity, the increased yield is more 40.6% and 18.3% than the stages of reviving-jointing and earing-ripening respectively.