The invention provides a connecting pipe sealing structure. The connecting pipe sealing structure comprises a first connecting pipe, a second connecting pipe and a sealing piece, wherein the first connecting pipe is provided with a groove, the second connecting pipe is provided with a protrusion, and the sealing piece is further provided with a through hole; and the protrusion of the second connecting pipe penetrates through the through hole of the sealing piece to be matched with the groove of the first connecting pipe, and the first connecting pipe is fixedly connected with the second connecting pipe. According to the connecting pipe sealing structure, the connecting pipes are matched with each other by adopting the concave and convex structures, the matching mode is tight, and the sealing piece sleeves the connecting pipes in a penetrating mode, does not make direct contact with the high temperature gas or liquid, and can be prevented from being eroded by the high-temperature gas.