the phase-sensitive amplification (psa) with an injected squeezed vacuum field is theoretically investigated in quantum-enhanced laser detection and ranging (ladar) receiver. the theoretical model of the amplified process is derived to investigate the quantum fluctuations in detail. a new method of mitigating the unflat gain of nonideal psa is proposed by adjusting the squeezed angle of the squeezed vacuum field. the simulation results indicate that signal-noise ratio (snr) of system can be efficiently improved and close to the ideal case by this method. this research will provide an important potential in the applications of quantum-enhanced ladar receiver.