Synthetic aperture ladar(SAL) is an ideal approach for the high resolution region observation with long distance. However, there is a contradiction between the azimuth resolution and the range swath in the single transmitter single receiver SAL system. So the range swath is restricted to a much narrow range. In this paper, the multiple-transmitter-multiple-receiver SAL system was proposed to overcome this limitation. The SAL system worked in the low pulse repetition frequency(PRF) mode to make the range swath unambiguous, and azimuth multiple-channels approach made the azimuth Doppler unambiguous by the way of combination virtue aperture and the real aperture through adaptive digital beam-forming method to realization the high resolution wide swath SAL imaging. The basic principle of increasing the azimuth resolution with the Multiple-Transmitter-Multiple-Receiver SAL system was depicted. Secondly, the concept of the Multiple-Transmitter-Multiple-Receiver SAL system mode was presented, and the signal model for the SAL mode was given as well. According to the Doppler ambiguous in the low PRF system, an adaptive signal processing approach was propoed to de-ambiguous. Finally, the simulation of Three-Transmitter-Three-Receiver SAL system was provided. The performance of the simulation shows the Multiple-Transmitter-Multiple-Receiver SAL system can overcome the Doppler spectrum aliasing and increase the azimuth resolution, and proves the feasibility of the Multiple-Transmitter-Multiple-Receiver SAL system.