Abstract: We study the characteristics of radio galaxy (RDG) and Narrow line Seyfert 1 (NLSY1) in the fourth Fermi LAT catalogue, the distribution characteristics of γ-ray flux and the RMS-Flux linear relationship. Based on these two types of active galactic nuclei in the data processing of γ-ray flux, the Gaussian function and log-normal distribution function are used to fit the flux distribution. By K-S test, S-W test, and reduced chi square χ². It is found that the distributions of RDG and NLSY1 are more consistent with the log-normal distribution than the Gaussian distribution, which indicates that their light variability may have nonlinear and multiplicative properties. In addition, linear fitting is also performed on two different groups of RMS-Flux for these two types of sources, and it is found that RMS-Flux has a strong linear correlation and its slopes are both positive.