There is no standard method for the Modulation Transfer Function (MTF) measurement of projection lens,so we analyze a real-time MTF measurement system based on image analysis for projection lens in this paper.Using CCD as an image receiver and based on image analysis,a method of MTF measurement is discussed.According to analyzing a single pixel image,the method can acquire tangential and sagittal MTF data at one measurement.The structure and theoretical model of the test system are expounded.The importance of system parameter calibration and how to calibrate correctly are emphatically analyzed.The factors that influence the results and how to correct the noise effect are also analyzed.Compared measurement results of a qualified projection lens and an unqualified projection lens with the designed datum,the comparison experiment show the validity of the system and the method.