Abstract: In order to study the effect of interference fit on circular arc gear machining, a mathematical model of circular arc tooth profile was established based on the end face coordinates of circular arc gear. Also, the helical surface equation was obtained according to the end face coordinates. Based on the circular arc gear model, the stress and deformation of interference surface between gear and shaft were analyzed, and the allowable maximum deformation and contact stress of the interface were solved. The effect of interference fit on the machining process was studied based on the deformation of tooth profile. The machining process of circular arc profile by bulb milling cutter was simulated, and the influence of deformation on the machining of tooth profile was analyzed. The results show that, the calculation and analysis methods can provide a theoretical support for the machining and selection of the interference fit between gear and shaft.