Simulation results from the Regional Atmosphere Modeling System (RAMS) were compared with observational data collected during the field experiment conducted in Lanzhou of Northwest China in December 2005. Simulation was carried out at a high horizontal resolution of 1 km under weak synoptic forcing, and from aspects of the boundary layer structure and the near surface variables over complex terrain. RAMS shows a reasonable ability to simulate the observed mixed-layer depth, surface temperature, and the diurnal variation of temperature and surface energy budget. The Mean Bias and RMSE for temperature is -1.73 ℃ and 2.16 ℃. The RMSE and RMSVE for surface wind are 1.61 m·s^-1 and 3.15 m·s^-1, respectively. Statistical analysis shows that the model performance is accepted for the studied area.