Abstract: The gradient bromating amorphous hydrogenated carbon films were prepared by low-pressure plasma chemical vapor deposition (LPPCVD) method using the mixture of bromoethane and hydrogen as source gas. The relationships of the film deposition rate and the hydrogen, and that of the bromine content and the bromioethane flowrate were described. The influences of the etching time and bromine flowrate on the main bounding state of the film CH C-Csp2 and C-Csp3 were analyzed. The results show that the deposition speed of the thin film decreases linearly with the increment of the hydrogen flowrate. Bromine content increases at first and then reduces with inreasment of the bromoethane flowrate. The longer the etch time and the lower the bromoethane flowrate are, the harder the prapared thin film is.