The signal process of a laser seeker was analysed on time domain when it was interfered by a suppressive laser jammer with high frequency. A laser guidance system with countermeasures acting as an interfered target and a high-frequency diode-pumped solid state laser acting as an interfering source,the interactional effect between them was tested from the view of systems on field. The angle errors between the sight of target and the optical axial of a laser seeker characterizing the interactional effect,although they show that the information processing mechanism of the laser seeker is damaged when the seeker receives high frequency laser signals so the seeker can not provide the angle errors of azimuth and elevation,the phenomena are disappeared when the suppressive jamming is removed.