Multi-stage oil well blowout preventer

The utility model relates to an oil well blowout preventer, in particular to a multi-stage oil well blowout preventer. The multi-stage oil well blowout preventer comprises a well mouth connecting flange, a blowout preventer, an anti-fall device, a greasing pump, an overflow groove and a hydraulic pump, wherein the well mouth connecting flange is connected with the blowout preventer; the anti-fall device is arranged on the blowout preventer, and connected with a greasing pump control head through a multi-section lubricator; the greasing pump control head is connected with the greasing pump, and connected with an overflow control head through a sealing pipe; the overflow control head is connected with the overflow groove through a stop valve, and connected with a hydraulic control head through a hydraulic pipe; and the hydraulic control head is connected with the hydraulic pump. The multi-stage oil well blowout preventer can switch off gas quickly when underground pressure is abnormal, prevents liquid from leak