The invention discloses a petroleum extraction well mouth return pressure control device. The petroleum extraction well mouth return pressure control device comprises a return pressure control device.Round grooves are machined below the return pressure control device, and supporting mechanisms are mounted on the outer sides of the front faces of two supports. Each supporting mechanism comprises afirst inclined plate, a first threaded rod, a first concave plate, a straight rod, a second inclined plate, a second concave plate, a first spring and a convex plate. The tops of the first inclined plates are rotationally connected with the left sides of the front sides of the supports. Through the cooperation of the supporting mechanisms, the round grooves and the supports, the supports are controlled to rotate in the round grooves to change the positions of the supporting mechanisms, fixing and supporting of the supporting mechanisms are facilitated, the trouble of manual filling and leveling is saved, the working difficulty is reduced, the practicality is improved, long-time vibration extrusion deformation is avoided, damage is avoided, the service life is prolonged, mounting is convenient, the operation is easy, the working efficiency is improved, petroleum is prevented from entering a connector, the trouble of cleaning is saved, next connection use is guaranteed, and the petroleum extraction well mouth return pressure control device is convenient to popularize.