In order to solve the problem of poor thermal stability and large influence of background light noise of the airborne long-distance single photon ranging laser， a design of the miniaturized， narrow line width， and low-energy laser suitable for an airborne environment is proposed. The laser adopts the main oscillation power amplification configuration. The seed source laser uses a reflecting volume Bragg grating as the coupling output mirror. Under the condition of 10 kHz repetition rate， the laser output with a line width of 0.035 nm is obtained， and the beam quality is Mx2=1.303 and My2=1.271. The optical-optical conversion efficiency is 44.4%. The amplifier adopts the innoslab configuration to amplify the laser energy， effectively alleviating the thermal problem and improving the beam quality. The Monte Carlo method is used to establish a single-photon ranging echo signal model， which verifies that improving laser performance can reduce the impact of laser jitter on accuracy. At the same time， the narrower linewidth output can use a matched narrowband filter to reduce background noise interference， thereby improving the accuracy of ranging.