The utility model provides a spindle locking block which comprises a cylindrical pedestal and an arched projection integrated with the cylindrical pedestal. The cylindrical pedestal includes a U-shaped gap in one direction, the caliber of the U-shaped gap is greater than or equivalent to that of a motor spindle, the arched projection wraps the U-shaped gap for a certain distance from one terminal to the other terminal of the U-shaped gap, a bolt hole is formed in the arched projection in the totally-wrapped side of the U-shaped gap at a position close to the terminal of the U-shaped gap, and the direction of the bolt hole is vertical to the axial direction of the cylindrical pedestal. The spindle locking block enables operation without power off.