This paper mainly discusses the analysis and judgment of abnormal knocking sound in automobile engines.First,the background and significance of the research,as well as related concepts and definitions,are introduced.Then,starting from the definition and characteristics of engine knocking sound,the possible causes of abnormal percussion sound of automobile engines are discussed,including fuel system problems and problems of internal mechanical parts of the engine.In terms of judgment methods,the article introduces in detail the manifestations of abnormal engine knocking sounds,the application of monitoring instruments,and the methods of manual inspection.In terms of treatment measures in different situations,the authors listed the treatment methods of slight percussion,severe percussion sound and abnormal percussion sound in different parts.In addition,the article discusses the importance of automobile engine maintenance and prevention of abnormal knocking sounds,as well as the impact and hazards of engine knocking sounds on driving safety.Finally,the paper summarizes the conclusions and looks forward to the direction of future research.This paper synthesizes theory and practical experience to provide a reference for the research and solution of abnormal knocking sound phenomenon in automobile engines.