The invention provides a mould clamping mechanism of an extrusion blow molding machine, which comprises a front template, a rear template, a front mould clamping arm, a rear mould clamping arm, a pullrod and a connecting seat of the front template, wherein the connecting seat is installed on the front mould clamping arm; the front template is articulated on the connecting seat by taking a horizontal direction as a rotating axis; an elastic mechanism for acting on the front template is arranged at one side of a rotating axle of the mould clamping mechanism; the applied moment of the elastic mechanism to the front template is reverse to that of the gravity to the front template; and a swing limiting mechanism of the front template is arranged at the other side of the rotating axle of the mould clamping mechanism. Due to the adoption of the technical solution, the front template can take the rotating axle as a rotary center to swing; and during the mould clamping process, the front template can automatically swing to the position at which is parallel to the rear template, thus effectively ensuring the parallelism requirements of mould parting surfaces, and leading the adjustment of the front template to become simple and easy.