For some types of newgeneration weather radar, there are problems such as instable detection, low success rate, and poor accuracy of antenna beam direction, as well as no antenna beam width and unsatisfactory measurement error detection of the full link echo intensity of the radar receiving system. Some improvements are conducted: (1) algorithm; (2) quality control method of data; (3) antenna control; (4) search mode of sun position; (5) reducing the rotating speed of antenna and increasing the acquisition resolution. The assessment shows: the detection accuracy of antenna beam direction using the improved sun method is significantly improved; the problems of instable antenna beam direction and low success rate are solved; the reliability and measurement accuracy can meet the requirements of echo intensity calibration using the sun method; and the error detection function of the whole link echo intensity measurement of the receiving system can be detected.