This essay describes a new method, based on fuel consumption and AFR (Air-fuel ratio) measuring, to acquire the charge efficiency of internal combustion engine. In the method, the fuel consumption and AFR under steady condition are used to calculate the air inlet, and the air charge efficiency is calculated by definition. The equations of air charge efficiency and error analysis were built on fuel consumption and AFR. An injector flux calibration & testing system and a measuring system of fuel consumption and AFR were designed for a ZS157FMI-3 motor equipping with ZH600 engine electronic control system. The charge efficiency was tested through measuring mean and transient fuel consumptions and AFR. The efficiency test result indicates that the two methods of measuring fuel consumption have a good consistence for charge efficiency calculation, and the error estimation of the test results demonstrates that the efficiency results calculated from the fuel consumption and AFR have high accuracy, with the relative error below 0.5%. Since the charge efficiency acquiring way overcomes some inherent drawbacks of the common methods such as pressure wave method and velocity-pressure method, it offers more measure accurate in theory and better adaptability to different fuel types.