The atomic force microscope (AFM) is a powerful and widely used tool for investigating micro/nano properties of surfaces. The force curve is generally used for measuring the surface interaction forces in AFM. In this study, dependence of force curve on relative humidity was investigated experimentally using the AFM in the environment-controlled chamber. It was found that the water meniscus bridge would be formed due to the capillary condensation of water vaper in the air when the relative humidity is higher than 70%.