The invention discloses a secondary resettling device for heparin, belonging to the field of biological pharmacy. The secondary resettling device comprises a pool body, a sludge discharging pipe, cant boards, a water inlet pipe, a water outlet pipe, a water outlet tank, a sludge returning pipe and a sludge collecting hopper, wherein the water outlet end of the water inlet pipe is located at the central part of the pool body; the water inlet end of the water inlet pipe is located above the water outlet end; a horn mouth is connected to the water outlet end of the water inlet pipe; a horizontally-arranged reflecting plate is suspended under the horn mouth; the cant boards are respectively arranged on two sides of the lower part in the pool body; the sludge returning pipe is arranged at the inner wall of the cant board adjacent to one side of the pool body; the water inlet end of the water inlet pipe is connected with the water outlet end of a sewage treatment pond arranged outside the pool body; the sludge collecting hopper is defined by the two cant boards at the bottom of the pool body; the sludge inlet end of the sludge returning pipe is inserted into the sludge collecting hopper; a sludge discharging opening is formed in the bottom of the pool body. The secondary resettling device disclosed by the invention has the advantages of simple structure, low investment cost, small occupied area and good settling effect; particularly, the secondary resettling device can be used for effectively intercepting and separating suspended solids which are not easy to precipitate in the sewage and is widely suitable for various wastewater treatment systems with high water quality of effluent.