Anti-play mechanism for cargo boom, cargo boom and crane

An anti-play mechanism for a cargo boom comprises a locking part and a gravity center adjusting part, the first end of the locking part is used for being rotationally connected with a knuckle arm, the second end of the locking part forms a hooking end, the gravity center adjusting part is fixedly connected to the side, away from the hooking end, of the locking part, and a balance weight piece is arranged on the gravity center adjusting part. The counterweight part can be movably arranged relative to the locking part so as to adjust the gravity center position of the locking part. According to the anti-movement mechanism of the cargo boom, the gravity center of the locking part moves on the two sides of the rotating center point of the locking part at different angles, the functions that the anti-movement mechanism is unhooked when the cargo boom is lifted, the cargo boom freely stretches out and draws back, and the anti-movement mechanism locks the telescopic joint arm when the cargo boom runs on a road are a