When tapping mode atomic force microscopy （AFM） is operated in air， the distance between the cantilever and the sample is so small that cantilever oscillation induces squeeze film air damping in the gap. This study aims to model and analyze the effects of squeeze film damping by using the Euler-Bernoulli and Reynolds equations. Theoretical analysis shows that squeeze film damping can decrease the damping coefficient depending on the distance between the cantilever and the sample and the cantilever width. Then， resonant amplitude and quality factor （Q） of the cantilever in multi-mode AFM are tested. Experimental results show that the Q of the fundamental resonant cantilever decreases obviously. The amplitudes of two cantilevers with widths of 20-2 μm decrease by 7.8% and 20.6%. Squeeze film damping can affect the cantilever with a large width to a greater extent than the cantilever with a small width. This phenomenon can also influence AFM dynamic characteristics； in particular， it can decrease flexural sensitivity and scanning speed. However， this phenomenon can only slightly affect the Q and amplitude of the cantilever. The impact of squeeze film damping of the cantilever is significantly reduced when AFM is operated in a higher-order resonant mode.