Aiming at the communications requirement of inter-satellite links laser ranging, a scheme of using four-quadrant detector as the communications detector and simultaneous tracking for the communications laser is proposed. The system can complete the communications and tracking missions in the condition of single detector. The corresponding communications and tracking compound mode experiment is established in laboratory and the detection performance which includes communications rate, limiting sensibility, photoresponse ability is tested. The calibration and extraction of communications laser miss distance is using low pass filter to deal with the modulate signal by the characters of Manchester code. When the laser spot could not cover all quadrants of the detector, the output communications signal is optimized and selected to improve the signal-to-noise ratio(SNR).The experimental results show that by using the PIN type InGaAs four-quadrant detector which photosensitive surface diameter is 1mm, the communication rate can achieve 10Mbps , the detection limiting sensitivity is -33 dBm and the SNR is 10-7。Initially the feasibility of four-quadrant detector in communications and tracking compound mode is confirmed and will lay the foundations for satellite miniaturization in future.