The Ag/TiO2 composite film was prepared on glass substrate by magnetron sputtering, while the influences of TiO2 film preparation parameters, including sputtering power, sputtering time, argon flow and vacuum degree on thermal insulation of Ag/TiO2 films were studied. Results showed that the temperature difference in thermal insulation firstly increased and then decreased with the increase in RF sputtering power, sputtering time, argon flow and vacuum degree. In terms of influence of the parameters on the temperature difference of the composite film, the importance degree in descending order was vacuum background, sputtering time, RF power, argon flow rate. The optimal combination of the four preparation parameters was with background vacuum of 4×10-3 Pa, radio power of 150 W, sputtering time of 15 min and argon flow of 20 mL/min.