Abstract: In this paper，the daily ET₀ and ET_c are calculated using K_c and FAO-PM from 1961 to 2000，and the evapotranspiration in every 10 days of wheat is estimated by the soil water balance equation．The real water consumption，as well as the degree of the water consum ption and requirements of wheat during the growing Season are established by using the soil water balance equation and means of correcting leakage of soil water and flow of precipitation every year．Based on this work，a loss estimation method on monitoring drought and estimating yield loss of wheat is established using functions of crop growth water and maxlimit of yield．The results show that the effects is satisfied and suitable form nitoring drought and estimating yield loss of wheat on mountainous areas of south Ningxia．