The utility model provides a clearance assembly device for lock pins of phase modulators. The clearance assembly device has the advantages that a mechanism movement combination mode is adopted according to characteristics of mechanical movement mechanisms, so that clearance assembly on the lock pins of the camshaft phase modulators can be simplified, the clearance assembly device is low in manufacturing cost, and the lock pins are good in clearance consistency; the phase modulators can be assembled without machining positioning pins, shells and positioning pin holes of cover plates, components and machining procedures can be reduced, accordingly, the manufacturing cost can be lowered, and the reliability of products can be guaranteed.