The utility model discloses a monitor for testing vehicle running conditions. The utility model is composed of an 8098 single-chip and single-board computer and an interface circuit which comprises a signal preprocessing circuit, a control signal output circuit and an alarm circuit. When a vehicle runs, the monitor can automatically implement processing and state analysis to more than ten parameters of engine oil pressure, water temperature, engine rotary speed, etc. The monitor can prompt to alarm when a signal is abnormal, and can automatically close an oil supply system of the engine when driving safety is endangered to ensure driving safety. The monitor can also print out the monitored signal data to provide a basis for vehicle maintenance, accident cause analysis, examination of technical levels of drivers, equipment acceptance, etc.