The electrical and optical properties of CdIn 2O 4 films produced by RF reactive sputtering have been investigated. The IR reflection R of the CdIn 2O 4 films as a function of oxygen concentration and heat treatment is discussed. Experiment results show that the IR reflection R of the CdIn 2O 4 films is very high, indicating that the CdIn 2O 4 films are good IR reflection films and can be used as heat preservation films.