In the paper the interaction mechanism was studied when multiunit and multispectrum detector system is irradiated by laser which is out of system wave band. For example , 1. 06μm laser was applied to detector system of three PC HgCdTe units , and unlike laser which is in system wave band , some new phenomena are found. Researches indicate that Ge window heated by laser is the ultimate reason that induces signal output of detector , and signal output curves of detector lie on resistance trait of detector when temperature of detector is changed.