Abstract: Based on single chip microcomputers,an automatic monitoring system for overall detection of the operating conditions of diesel engine is presented.The system can be used to measure rotational speed of the engine,temperature and pressure of lubricating grease,temperature of cooling water,etc.Furthermore,by data analyzing,the system can give warning if any overrun occurs and stop the engine if runaway phenomenon exists.The measuring principles are discussed in detailed,and the corresponding circuits and block diagram of the system are given in this paper.