Spatial positioning error causes false echoes and affects the reliability of radar observation data, resulting in interference on forecasts directly. Our project team acquired 17 cases from the nationwide CINRAD/SA radar stations. Combining with flow direction of antenna servo system signal and parameter characteristics of key components, this paper gradually analyzes the factors conducing spatial positioning error and summarizes the method of diagnosing such problems. Finally, three representative cases are analyzed, which provides guidance for removing such malfunction quickly.