The invention belongs to the technical field of waterproof sealing of a rotation mechanism of a lorry-mounted crane, and provides a dual-seal rotation sealing structure, arranged on a vertical column, of the lorry-mounted crane. According to the technical scheme, a cover plate assembly is arranged in the lower portion of the vertical column in a sleeved mode and is fixedly connected with a base assembly through bolts, a sealed cavity is formed between the vertical column and the base assembly, a rotation connector and a rotation bearing are installed in the sealed cavity, an upper sealing groove and a lower sealing groove are formed in the circumferential surface of the vertical column, the upper sealing groove is located above the cover plate assembly and provided with an L-shaped sealing ring, one end of the L-shaped sealing ring is fixed in the upper sealing groove, the other end of the L-shaped sealing ring covers the cover plate assembly, one corner, uncovered by the L-shaped sealing ring, on the upper portion of the cover plate assembly is cut to be like a slope, the lower sealing groove is located between the cover plate assembly and the contact surface of the vertical column, and an O-shaped sealing ring is installed in the lower sealing groove. The sealing structure is mainly installed on the rotation mechanism of the lorry-mounted crane for achieving waterproof sealing.