Abstract: Based on the large area stratus precipitation observation in 2011 by the upgraded C-band dual-linear polarimetric Doppler radar on wheel (CPDRW) which was built in the State Key Laboratory of Severe Weather (LaSW),Chinese Academy of Meteorological Sciences (CAMS),the improvement of radar's measurement quality and its detection ability arc discussed. The dependencies of the differential reflectivity ZDR and the cross-correlation coefficient ρHV (0) on the signal-to-noise ratio SNR,and the stability of the radar system initial differential phase arc analyzed. After radar upgrade, the detectable threshold of SNR for ZDR and ρHV (0) is improved to 15 dB from 25 dB. Moreover, the system initial differential phase is more stable and its volatility with the elevation angle and the time becomes smaller, and ZDR becomes more steady with the change of SNR as well. The calibration of ZDR by using the vertical incidence method is conducted and improved. The specific differential phase KDP, calculated from the differential propagation phase shift ΦDP processed using the classification processing method becomes smoother and more reliable. According to the conventional characteristic and the polarization properties of ground clutter, the ground clutter and mixed echo detection algorithm is developed by using the fuzzy logic method. The detection performance of the algorithm is evaluated. The results of analysis indicate that both the comprehensive detection algorithm which combines regular parameters with polarization parameters and the conventional detection algorithm can identify ground clutter well,but the comprehensive recognition algorithm has more obvious advantage in the classification of echoes near the zero radial velocity area and the case of mixture of ground clutter with precipitation echoes than the conventional recognition algorithm.