Oscillating buoys are used to capture wave energy in point-absorbing wave energy converters, and they are also subjected to wave slamming while working. The loads generated by wave slamming may cause damage to wave energy converters. It's particularly important to take wave slamming phenomena into consideration during the design process of wave energy converters, especially the buoys. Experimental method is adopted to study the wave slamming pressure characteristics of oscillating buoys by changing wave parameters. According to the test results, it is found that: (1) The bottom slamming and side slapping pressure of the buoy is significantly greater than other conditions when the period is about 1.5 s. (2) As the wave height increases, the position where the buoy is slammed moves from outside to inward in the radial direction on the bottom. (3) Side slapping is the main form of wave slamming on the buoy. The slapping pressure is much greater than bottom slamming and overtopping slamming. The effect of overtopping slamming only exists when the wave height is large.