In order to improve the resolution of image scanning microscopy, we present a method based on image scanning microscopy and radially polarized light. According to the theory of image scanning microscopy, we get the effective point spread function of image scanning microscopy with the longitudinal component of radially polarized light and a 1AU detection area, and obtain imaging results of the analyzed samples using this method. Results show that the resolution can be enhanced by 7% compared with that in image scanning microscopy with circularly polarized light, and is 1.54-fold higher than that in confocal microscopy with a pinhole of 1AU. Additionally, the peak intensity of ISM is 1.54-fold higher than that of a confocal microscopy with a pinhole of 1AU. In conclusion, the combination of the image scanning microscopy and the radially polarized light could improve the resolution, and it could realize high-resolution and high SNR imaging at the same time.