Abstract: The valve seat made of 05Cr17Ni4Cu4Nb stainless steel material features a deep small hole (diameter 0.75 mm, depth 4 mm) that serves as a critical structure for controlling fuel flow, with stringent quality requirements. Addressing the issue of inappropriate selection of the existing cutting parameters, which sometimes leads to non-compliance with the design requirements for the roundness of the hole mouth and damage at the entry point of the hole mouth during the machining of deep small holes, this paper employs single-factor experimental and orthogonal experimental methods to study the influence of the cutting parameters on cutting force, selects the most suitable combination of cutting parameters, and finally verifies the optimization effect through experiments. The results indicate that the cutting force increases with the increase of depth of cut, feed rate, and spindle speed. The order of influence on cutting force is feed rate > depth of cut > spindle speed. The optimal combination of cutting parameters is a depth of cut of 0.010 mm, a feed rate of 0.003 mm/r, and a spindle speed of 750 r/min. Using a miniature triaxial acceleration sensor, experiments were conducted to process deep small holes with optimized and non-optimized cutting parameters. Compared with the non-optimized parameters, the optimized cutting parameters resulted in a 43.55% reduction in axial acceleration, a 41.95% reduction in radial acceleration, and a 46.51% reduction in tangential acceleration of the tool, effectively reducing tool chatter and significantly improving the machining quality of the hole entrance.