When it comes to GDI start-stop technology,the control of final stop crank angle can never be neglected.The probabilitydistribution of this final angle could be obtained via repetitious engine stop experimental method,the principle of which however,could not.As a result it seems impossible to get a concise control on the engine stop process.Dynamic model engine stop has been established,simplified and modified in order to identify the key factors that have an effect on engine stop.The model was verified by relatedexperiment to address the simulation demands.The analysis on simulation results provide us several essential conclusions that the factors,specifically heat transfer and leakage as well as the initial speed in compression top dead center of final stroke,will cause a stronglydifferent piston final position.The engine final position will be relatively located in the range 0~10℃A,60~90℃A ATDC.