In this paper a brief review of the optical methods based on the simultaneous interpretation of the different optical experimental data obtained for thin film systems is presented. These methods are known as the multi-sample methods. It is shown that these optical multi-sample methods are very useful for analyzing many thin film systems. In particular it is illustrated that selected optical multi-sample methods are powerful for studying the following problems: investigations of growing the native oxide layers on the semiconductor surfaces; suppression of the influence of the transition interlayers between the substrates and thin films and determination of the optical constants of bulk materials. Concrete experimental examples demonstrating the foregoing statements are presented in this paper as well.