The invention relates to the field of machining clamps and aims at providing a clamp for acceleration motor shell end hole machining and a clamping method. The clamp for acceleration motor shell end hole machining comprises a base with a vertical plate. The clamp for acceleration motor shell end hole machining further comprises a front platen with multiple pressing assemblies at the rear end, multiple positioning core cylinders arranged in a coaxially sleeving manner, a rear platen, a bolt, a fixed nut and a positioning assembly. The outmost positioning core cylinder is sleeved with the vertical plate. The vertical plate is connected with the rear portion of the outmost positioning core cylinder. A screw of the bolt penetrates the rear platen, the positioning core cylinders and the front platen and is connected with the fixed nut in a threaded manner. The outer positioning core cylinder in every two adjacent positioning core cylinders is provided with an adjusting screw hole and rear end of the other inner positioning core cylinder is provided with a protruding ring connected with the corresponding adjusting screw hole in a threaded manner. By the adoption of the clamp for acceleration motor shell end hole machining, end holes of acceleration motor shells of various specifications can be machined, and universality is good.