The invention discloses a mono-cone bit with a PDC combined tooth and belongs to the technical field of drilling devices of petroleum and natural gas, mine engineering, building foundation engineering construction, geology and hydrology and the like. The mono-cone bit comprises a bit body and a cone, wherein the cone is rotatably connected with the bit body; cutting teeth are arranged on the cone; at least one of the cutting teeth on the cone is a PDC combined tooth; the PDC combined tooth is formed by combining two PDC teeth; each PDC tooth consists of a body and a polycrystalline diamond layer covering more than 60% of the support surface of the body; the combination manner of the two PDC teeth is characterized by enabling the polycrystalline diamond layers to fit closely and clamping the polycrystalline diamond layers by two bodies on the outer side to form a four-layer sandwich structure; when the PDC combined tooth is arranged on the cone, an included angle between a normal line of the polycrystalline diamond layer fitting surface of the PDC combined tooth and a normal line of a cone contour curved surface at the arrangement point of the PDC combined tooth on the cone is 75-90 degrees. Through the PDC combined tooth, the rock breaking efficiency of the mono-cone bit can be improved, and the service life of the mono-cone bit can be prolonged.