ZDR Processing algorithm of C-band mobile dual polarization radar was recommend. First the effect of SNR on parameter ZDR was analysed. The result shows that SNR should be at least more than 18 dB, then ZDR data can be credible; secondly the effect of blockage around radar on ZDR was analysed,The results show that the pointed shape blockage is easy to cause the ZDR positive deviation, the house and building is easy to cause the negative bias, while the shelter of the woods, the positive and negative deviation of great change. With the decreasing degree of occlusion, changes in amplitude of ZDR becomes small; aiming at the system biases of ZDR, put forward the method by combining reflection factor and ΦDP increment to judge light rain area and get it, from the time series analysis of ZDR system bias, we concluded that the ZDR system bias must be adjust in time; in the end, Using the FIR filtering method for KDP calculation and use it for attenuation correction; Aiming at work application, provide the transaction flow diagram for real-time processing ZDR parameter.