Cosmological hydro-dynamical simulations enable us to trace the galaxy evolution history self-consistently and test the galaxy formation theories by comparing with the observations. In my work, I studied the connection between infall dark matter halos and satellite, focusing on the effects of the dark matter halo formation history on the further evolution and properties of satellite galaxies. Besides, I also studied the HI gas in the massive passive galaxies in this simulation. Large amount of HI reservoir does exist in some passive galaxies, as revealed by the work of Zhang et al (2019) using observational data. The cold gas content in the passive galaxies can be used to constrain the AGN feedback models.
