Abstract: In order to investigate potential applications of the 1.8m telescope equipped with an auto-guiding stellar adaptive-optics system at the Lijiang observational station, we give a preliminary performance evaluation of this adaptive-optics system by using the theory of scaling of residual phase variances proposed by us. The results show that under usual observational conditions the angular resolution of the system is almost diffraction-limited. We also give an analysis of the performance when a laser guide subsystem is equipped on this adaptive-optics system, and our calculations show that the sky coverage will be consequently greatly improved.