Abstract: Considering the vacuum degradation caused by material desorption, the correlation mechanism between bombardment angle and material desorption yield was studied. The desorption characteristics of zirconia ceramics, Au-coated ceramics and Au-coated stainless steel were tested by using a 143 KeV/u Bi³²⁺ ion beam through the self-developed desorption yield test device with adjustable angles. The results show that the desorption yield increases significantly with the increase of incident angle. The proportion of H₂ increased rapidly during bombardment. The desorption yield of zirconia ceramic can be reduced by about 50% after gold plating, while the difference in desorption yield between gold plated samples on different substrates is less than 15%. It is confirmed that the desorption process is mainly dominated by the physical and chemical properties of the surface, and the substrate has little effect. Based on the theoretical model of sputtering yield and incident angle, the surface effect correction coefficient α was introduced to modify the desorption model and verified. This study provides a theoretical model and experimental basis for the engineering prediction of particle desorption yield in the vacuum system.