Abstract:Unusual echoes on 3 April and 3 July, 2013 are studied by CINRAD/SA and radiosonde data. The results indicate that radar servo system faults resulted in the dislocation of scan line azimuth, which led to the silk shaped echoes on 3 April 2013 The unusual echoes on 3 July contain cloud and super refraction radar echoes. The reason why the area of 15° was greater than 05° is that the engineer did not adjust time appropriately, and the radar system was adjusted by using wrong calculation data while calibrating radar beam pointing on April 6 The formula and algorithm of parameters for the calibration of radar azimuth and elevation by the solar method are given, and the fault phenomenon is imitated. It is pointed out that the error data generated by radar hardware faults and calibration errors have influence on forecasters in analyzing weather correctly. The data quality control method for silk shaped echoes is introduced. It is suggested that a high precision time service system should be equipped at radar sites, which can provide experiences and scientific evidences for super refraction echo identification and radar routine maintenance.