A typical model of the relay mirror system is established, and the appropriate styles of the two adaptive optics installations used in a relay mirror system are analyzed according to the different working conditions and different uses. It is recognized that the adaptive optics installation located at the light source may use the conjugate adaptive optics, the adaptive optics installation located on the platform may use the optimization algorithm based adaptive optics. Based on a laser relay mirror system under the Hufnagel-Valley 5/7 at atmospheric turbulence model condition and with target height of 25 km, platform height of 30 km, and downlink aiming precision of 1 μrad, necessarity of the second adaptive optics installation its influence on the system performance is analyzed. Performances of beam propagation through the relay mirror system with certain correction precisions of 0, 5th, 10th, 20th and 50th order as well as ideal correction condition are simulated, results show that the two adaptive optics installations have a great impact on the system performance improvement, uplink power efficiency can be improved from 58.82% to 81.27% and power proportion in 0.5 cm bucket at the target can be improved from 1.07% to 15.85% under closed-loop mode with ideal adaptive optics precision.