Based on the division of Sanxia region into several conditional climatic homogeneous rain areas, the climatic Z-R relationships that vary with the range from radar were derived for different rain patterns such as the convective, the mixed-thunderstorm, and the mixed-shower by using of the first moment PMM proposed by Atlas. These relations can be used to comprehensively correct radar measuring error caused by the effects of the beam average and the C-band attenuation, etc.