Abstract: The geometric properties of surface asperities have important effects on surface adhesion and friction in tribological systems. In order to study the effect of roughness on adhesion, etching of the silicon wafers using KOH solution was performed to get eight samples with different roughness. In this paper, the effect of RMS on adhesion was studied by using atomic force microscope (AFM). Two AFM probes were used to simulate different contact geometry. The one had a flat with a diameter ~ 2 μm and the other one had a sharp tip. The experiments were performed under the ambient condition and in the glove box. Then 15 points were selected for measuring the adhesion force and 50 measurements were performed on each point, and the average adhesion force and standard deviation of the sample were determined according to the calculated values. Finally, comparison on the experiment value to the calculated results from Rabinovich model was made. The results show that in case of relative small RMS, the adhesion force decreased sharply with increasing RMS, and the trends fitted the Robinovich model well, as the RMS was large, the adhesion force unobviously increased with increasing RMS, and a larger difference was found to Rabinovich model.