The invention belongs to the technical field of buffering devices, and particularly relates to a piston-type hydraulic buffer with small size, comprising an external cylinder base, an external cylinder body, a throttle lever, an oil nozzle, a plunger piston, a plunger piston base, and a plunger piston upper cover; the external cylinder base is provided with the external cylinder body and the throttle lever, and the throttle lever is positioned inside the external cylinder body; the external cylinder body is communicated with the oil nozzle, hydraulic oil is injected into the external cylinderbody through the oil nozzle; the interior of the external cylinder body is matched with a sliding-type plunger piston in a sealing way, the lower part of the plunger piston is sealed by the plunger piston base which is provided with an orifice, the throttle lever passes through the orifice in the plunger piston base, and the throttle lever is in variable clearance fit with the plunger piston base; the upper port of the plunger piston is sealed by the plunger piston upper cover; the interior of the plunger piston is provided with a piston ring in a sealed sliding matching way, and the plunger piston is provided with an energy-accumulation device. The piston-type hydraulic buffer solves the technical problems of unstable buffering performance, poor performance repeatability and short service life which are caused by the mixing of oil and gas in the buffering process in the prior art, and simultaneously reduces the structural size of the buffer.