Abstract: The smoothness and accuracy of volumetric efficiency calibration data for VVT engine affect the engine air-fuel ratio control accuracy. Thereby, they affect the performance of vehicle emissions, vehicle drivability and fuel economy. In this paper, the volumetric efficiency of the calibration data is ptimized by using adaptive look-up table method with MATLAB software. Optimize Volumetric efficiency formula V=a+bx+cx², Constant a, coefficient b and the quadratic coefficient c are optimized. The engine volumetric efficiency calibration data are smoother, there is no great fluctuation between adjacent points. Before and after optimization, the main data deviation does not exceed 5%, which meets engineering application requirement.