The invention relates to a gain modulation impulse imaging laser radar system. The beam emitting from impulse laser of imaging device would irradiate to target after reforming by optical transmitting antenna. Echo impulse would emit to light input end of intension imagine device of target intension image. Monotone alteration modulation signal output end of high voltage modulator connects to the gain modulation signal control end of imaging device. The exposure control end of control processor connects to switch control end of intension imaging device. The invention could effectively improve acceptance range and imaging quantity and decrease the complex degree of system structure.