Results from experiments measuring surface layer turbulence in Northwest China are presented. The measurements are taken over two years using surface layer atmospheric parameter system and differential image motion monitor.The surface layer atmospheric parameter system is composed of HTP-2 microthermal sensors and WXT520 meteorological sensorsis placed at 2 m and 6 m on a mast. Microthermal sensors are used to measure structure constant of refractive index and meteorological sensors are used to measure meteorological parameters. It is observed that structure constant of refractive index in the surface layer falls with exponent altitude dependence with the power index of -0.8 in the day and -0.3 at night. The contribution of surface layer to the integral turbulence is estimated using coherence length ratio. Coherence length ratio changes in a diurnal cycle with large values in the day and small values during the night and the changing trend and monthly averaged values are different between months. Discussion of relationship between local seeing and meteorological variables shows that local seeing correlates with temperature difference positively in the day while negatively during night. Based on longtime experiments, the results are credible and valuable in the work of site-testing and optimizing the performance of adaptive optical systems.