In this paper, the main factors influencing thermal conductivity of diamond film were analyzed in theory. The thermal conductivity of diamond film was measured by means of the photothermal deflection method, Various crystal structures of diamond films were obtained by synthesis with various deposition methods and conditions. Diamond films synthesized under lower concentration of methane and technique of annealing by MWPCVD method have higher thermal conductivity. Thermal conductivity of diamond film increases with the increasing of removal thickness for the SiC layer on the back of the film. (100)-oriented diamond thick films have higher thermal conductivity.