The invention discloses a rotary polishing device and method for blind hole polishing. The rotary polishing device comprises a workbench, a movable positioning assembly, a flow pass assembly and a rotary clamping assembly. The movable positioning assembly comprises a horizontal module mounting rack, a horizontal straight line module, a horizontal module driving motor, a vertical straight line module and a vertical module driving motor. The rotary clamping assembly comprises a rotary motor, a motor mounting base, a bearing, a supporting block, an auxiliary clamping head and a vertical mountingbase. The flow pass assembly comprises a main clamping head, a rotary joint fixing base, a flow pass fixing plate, a sliding rail connecting plate, an extraction opening check valve, a gas-liquid abrasive particle flow joint, an abrasive particle flow inlet valve, an air pressure opening check valve, a flow pass joint, a flange-type rotating joint and a main clamping end O ring. By adoption of therotary polishing device and method for blind hole polishing, blind holes of blind hole type workpieces can be polished, the rotary motor can be used for driving the workpieces to be machined to rotate in the machining process, abrasive particle flow can impact the inner walls of the blind holes in a more unordered mode during machining, and machining efficiency of the blind holes is improved.