The utility model relates to a slag pot self-locking clamping device, which is arranged on a support tipping frame and is used for clamping a slag pot with a trunnion. The clamping device comprises two groups of clamping mechanisms arranged at two sides of the slag pot mutually symmetrically, with each group of the clamping mechanisms comprises: a clamping arm, a connecting rod, a crank and a driver, wherein the middle of the clamping arm is supported on the support tipping frame in an articulating manner and one end of the clamping arm is clamped with the trunnion while the other end of the clamping arm is hinged with the connecting rod; two ends of the driver are respectively hinged on the support tipping frame and one end of the crank; the crank, which is a revolving member, is hinged with the connecting rod at the other end thereof, the middle of the crank is supported on the support tipping frame in an articulating manner and drives the connecting rod to implement plane motion under the driving of the driver in order that the clamping arm movably clamps the trunnion. The slag pot self-locking clamping device is convenient for installation, is self-locking after clamping and iscapable of ensuring good safety and reliability during the tipping of the slag pot, thus increasing operational dependability of slag pot mechanism and lessening hidden danger of accident.