Abstract: A side mold working mechanism includes a cavity plate defining a mounting groove forming a receiving hole. Bilateral sides of the mounting groove hollow toward bilateral sides of the cavity plate to form two hollow grooves. Two guide blocks disposed in the hollow grooves have a leading track. The guide block defines a locating recess communicating with the leading track. Two locating blocks fixedly mounted in the locating recesses have a preventing portion placed on the leading track. A slide is movably assembled in the mounting groove. Bilateral sides of the top of the slide protrude outward to form two shoulders slidably supported by the leading tracks and capable of being blocked by the preventing portions. The top of the slide defines an inclined groove and an angular pin has an inclined bottom end for being inserted into or withdrawn out of the inclined groove from the receiving hole.