The invention discloses an automatic subcultivation type blood cultivation instrument which comprises a culture bottle, a pump body and a plunger. A compression cavity is formed inside the pump body,the upper side of the compression cavity is communicated with the interior of the culture bottle through a puncture needle, a first one-way valve is arranged on the puncture needle, a nozzle is arranged at the lower side of the compression cavity, the plunger is arranged inside the compression cavity and can move back and forth in the axial direction of the compression cavity so as to extrude/expand the space inside the compression cavity, a transmission mechanism is connected to the rear end of the plunger, a sealing head is arranged at the front end of the plunger, and the outer wall of thesealing head is in sealed contact with the inner wall of the compression cavity. By adding the pump body and the plunger to the culture bottle, the culture bottle and the compression cavity inside thepump body are communicated through the puncture needle, when the plunger is moved backwards, space inside the compression cavity is expanded, a blood sample enters the compression cavity, when the plunger is moved forwards, the space inside the compression cavity is extruded, the blood sample is thrown out through the nozzle, the effect of automatic subcultivation is achieved, the efficiency is quite high, and the functions of quantitive liquid dropping and drop liquid speed control can be achieved.