Abstract: Crop coefficient is one of the most important parameters needed for crop water requirements using the reference crop method. In this paper, crop coefficients of spring wheat (k_c) were calculated by using the water balance method. The change of k_c during spring wheat growing period in windy dust area was analyzed. The k_c as functions of days after planting (DAP) and cumulative growing degree (CGD) were derived, and the third k_c was derived from the data using the FAO "Straight-Line" Method. The results showed that there were good sixth-order polynomial and forth-order polynomial relations between k_c and DAP and CGD, respectively. The high coefficients of determination (R²>0.94) for the DAP and CGD regressions indicate that the curves fit the data well. The three typical k_c values, derived by using the FAO "Straight-Line" Method at the initial, middle growth stages and at harvest data were 0.57, 1.70, 0.55, respectively.