Negative-pressure mechanism for ligation device and ligation device

The invention relates to the field of medical instruments, in particular to a negative-pressure mechanism for a ligation device and the ligation device. The negative-pressure mechanism is characterized in that an air cylinder is arranged in an air cylinder barrel, a piston is arranged in the air cylinder and sleeved with a piston reset spring, the two ends of a negative-pressure generation connecting rod mechanism are connected with a negative-pressure handle and the piston respectively, the end, far away from the negative-pressure generation connecting rod mechanism, of the negative-pressurehandle is hinged with the negative-pressure mechanism body, the negative-pressure generation connecting rod mechanism comprises a fixing support and a connecting rod, the two ends of the connecting rod are hinged with the negative-pressure handle and the piston respectively, the middle end of the connecting rod is hinged with the fixing support, and a one-way valve is arranged at the top end of the air cylinder. The ligat