The utility model provides a square cone-shaped steel coal bucket lining piece of a heat-engine plant coal handling system. A steel coal bucket is square cone-shaped. Stainless steel plate triangular spliced blocks, rectangular spliced blocks and right-angle ladder-shaped blocks are arranged and welded on the inner wall of the steel coal bucket in a regular pattern so as to serve as a lining. Stainless steel sticking angle shafts are arranged on the intersecting portion of two adjacent faces of the inner wall of the square cone-shaped steel coal bucket. The butt joint space between the stainless steel splicing blocks is 3 millimeters to 4 millimeters. Plug welding holes are formed in each stainless splicing block in a space of 250 millimeters to 300 millimeters. The steel coal bucket lining stainless plate is the equal that a protection layer is added to the inner wall of the steel coal bucket. The functions of the protection layer are to prevent the steel coal bucket substrate from being abraded and corroding, reduce friction coefficient of the inner wall of the steel coal bucket, and then avoid blocking of an outlet of the steel coal bucket due to bonding of coal grains. The lining stainless steel plates are long in service life.