Dual polarization X-band radar data and ground-based automatic rain gauge data were analyzed for precipitation estimation in summer of Beijing in 2009. Firstly, the low pass filtering and attenuation correction methods were used for controlling the quality of radar data. Then two relationships of X-band radar parameters and rain rate were established, i.e.Z_h=159R^1.37 and R =13.9K_dp ^0.81, after the specific differential propagation phase (K_dp) was extracted. Finally the comparison analysis was made between the rain rates estimated from the two relationships and the corresponding ground data. The results indicate that the rain rates estimated from the two relationships have a good consistency with the ground data. In addition, when the rain rates are greater than 10 mm·h^-1, the estimated rain rates from K_dp-R are more accurate and stable than that from Z_h-R. Also, the average standard deviation analysis shows that the estimation accuracy of K_dp-R is significantly higher than Z_h-R.