The invention provides a trajectory adjustment and movement conversion mechanism of a reciprocating movement part. The mechanism comprises an external support piece which is provided with a first straight tube part shaped as a straight tube, an elastic piece which is used for receiving pressure and torque to store elastic potential energy and provide an elastic force outward, a mobile piece of which the rear end is arranged on the front end of the elastic piece, an internal support piece which is provided with a second straight tube part shaped as a straight tube, and a position control structure. The second straight tube part is arranged in the external support piece in a sliding manner; the elastic piece is arranged in the internal support piece, and the rear end of the elastic piece is fixed in the internal support piece; and the mobile piece is arranged in the second straight tube part in a rotation and linear movement manner. The position control structure is arranged on the external support piece and the internal support piece, and is connected with the mobile piece to lock and release the mobile piece so as to enable the mobile piece to move along the second straight tube part when the elastic piece releases the elastic potential energy. The mechanism provided by the invention has the advantages of simple structure, flexible control and low manufacturing cost.