In this paper, one method is proposed to test the echo difference between two adjacent radars’ overlap areas. The reasons of the difference can be divided into external and internal factors. The external factors include occlusion, ground/AP clutters, atmospheric attenuation, etc. and all of these external fact-ors are removed by this method. The spatio-temporal consistency is matched according to the relationship between raindrop diameter and falling speed. Then, the reflectivity factors between two radars are compared. If significant difference still exists, it is due to some internal factors. In addition, the paper also discusses two cases, one is the malfunction of frequency source in Zhengzhou Weather Radar, and the other is the squall line in Guangdong Province. Based on the two cases, the method is proved to be able to test the reflectivity difference effectively. Thus, this method could have high application values in weather radar real-time monitoring operation. If reflectivity factor of one radar differs from other radars nearby, the information can be quickly transferred to the maintenance workers so that they can check and solve the problem in time.