The invention provides a composite rubber extruder head locking mechanism. Locking hydraulic cylinders push piston rods to stretch and retract to drive wedge-shaped locking blocks to move front and back, and then locking or unlocking of a composite extruder head is achieved. Moreover, locking holding depends on mechanical self-locking of locking surfaces during normal extrusion operation. Through the modes of swing opening and closing of a lockable door and locking of the wedge-shaped blocks, the structure is simplified, cost is lowered, operation is facilitated, no impact is produced during operation, and the wedge-shaped blocks are free of bending stress during work.