Abstract: In high-frequency satellite laser ranging (SLR) system, the flight time of laser pulse is acquired by an event timer(ET) which measures the event epochs of laser transmitting and photon receiving. In order to put an ET with higher frequency and precision into good use, the GT668SLR-1 type from Guidetech is introduced into the 1.2m telescope SLR system during our system upgrading, its principle and structure are analyzed. By means of measuring fixed signals from signal generator, ground target measurement and satellite laser ranging, the new event timer is tested for the SLR system, and the processing results of sampled data meet the demand of ranging standards. Therefore, it is concluded that the GT668SLR-1 type is capable to be integrated as the time measuring unit for the SLR system.