The invention relates to a half-blind hole and blind hole hydraulic cylinder inner wall ultrasonic finishing method, belongs to the technical field of hydraulic cylinder machining, and provides the half-blind hole and blind hole hydraulic cylinder inner wall ultrasonic finishing method with simple operation and for effectively improving the cylinder barrel inner wall roughness and the machining precision. The half-blind hole and blind hole hydraulic cylinder inner wall ultrasonic finishing method comprises the following steps: firstly, inner walls of a half-blind hole and a blind hole of a hydraulic cylinder are roughly machined to build a half-finishing reference; then, the half-finishing is performed for the inner walls of the half-blind hole and the blind hole of a hydraulic cylinder to build a finishing reference; the finishing is performed for the inner walls of the half-blind hole and the blind hole of the hydraulic cylinder; finally, the inner walls of the half-blind hole and the blind hole of the hydraulic cylinder are ultrasonically vibrated after finishing treatment; and in ultrasonic vibration, surfaces of workpieces are continuously impacted by a tool head with ultrahigh frequency, and meanwhile, a cutter performs a feeding motion. The half-blind hole and blind hole hydraulic cylinder inner wall ultrasonic finishing method is widely applied to machining of the inner walls of the half-blind hole and the blind hole of the hydraulic cylinder.