In traditional on-orbit modulation transfer function (MTF) measurements based on periodic targets, there is a known overdependence of the achieved accuracy on the number of target groups. The method introduced in this study aims to overcome such reliance, through a thorough analysis of the principle of the traditional method. We first collect the imaging data of multiple groups of ground periodic targets with certain phase differences and then calculate the output modulation of the imaging system by parametric fitting using all the sampling data as well as the relative phase relations. Subsequently, we compare the input and output modulations to obtain the MTF. We also perform a simulation and a series of experiments of real remote sensing cameras to assess the effectiveness of our method. The results theoretically reveal a small measurement error of less than 0.5% using only two groups of targets, whereas the errors caused by image noise and target-periodic- and measuring-angle matching deviations are less than 4%. This method has good adaptability, and is consistent with the slanted-edge method; therefore, it can be easily applied to on-orbit MTF measurements of high-resolution optical remote sensing cameras.