The rule of germanium material temperature changing with incident laser power density and irradiated time under spectral unrelated laser irradiating is obtained, and the radiation characteristics of infrared detecting systems are influenced with the material temperature rise. The experimental results of germanium material characteristic changing irradiated by spectral unrelated laser are analyzed, which indicates that germanium material transmissivity will be reduced for material temperature rise, and the performances of the detecting system are influenced. The study will be used for improving of the design and application of infrared systems.