The utility model relates to a well head control mechanical device for an oil (gas) extracting well in the production of an oil field. The utility model is especially suitable for a thick oil thermal production well. The utility model is mainly composed of an adapting joint 1, a press cover 2, slip 7, a slip seat 8, a main body 9, etc., wherein a cavity is designed on the lower part of the adapting joint 1, high pressure liquid can be injected in the cavity of the adapting joint 1 by a valve body, a flow passage can be opened by a compression spring, and the inner wall of the cavity of the adapting joint 1 is thin so as to generate contraction following the increase of pressure; thus, a sleeve pipe 6 can be tightly clamped. When a pump stops, a valve core closes the flow passage of the cavity under the action of the spring as to prevent the high pressure liquid from leaking. Because the technical scheme is used, when the utility model is used for assembling, the utility model can realize seal under the condition that welding operation needs not to be performed. Meanwhile, the adapting joint 1 can be replaced after damaged.