The invention relates to a mechanical arm end two-section-type stabilizing device for craniotomy. The device comprises a fixing module, a first-stage cushioning module and a second-stage cushioning module, the fixing module comprises a fixing frame and an L-shaped connecting plate, the fixing frame comprises a first horizontal plate, a second horizontal plate and a vertical plate, the two ends ofthe vertical plate are connected to the edges of the same sides of the first horizontal plate and the second horizontal plate respectively, one end of the L-shaped connecting plate is connected to thevertical plate, and the other end is connected to an end joint of a mechanical arm; and the second-stage cushioning module comprises a lower supporting plate and two cushioning units, each cushioningunit comprises a guide rod, a cushioning spring and a limiting unit, the first-stage cushioning module comprises two supporting leg units, and each supporting leg unit comprises a supporting pipe, asupporting leg spring, a sliding block and a supporting rod. Compared with the prior art, the device has the effects of buffering and protecting two times of drilling and milling force sudden changes,guiding the track of the end of a drilling and milling cutter, relieving the holding strength of a doctor on instruments an operation and preventing stall instability.