The invention relates to an on-column switch and a lead-out shaft sealing structure. The lead-out shaft sealing structure comprises an annular sealing groove arranged on a lead-out shaft. A sealing ring used for forming sealing cooperation with a box body through hole is arranged in the annular sealing groove. The sealing structure comprises a positioning groove arranged on the shaft body of the lead-out shaft. A sliding bearing used for forming slide support cooperation with the box body through hole is arranged in the positioning groove. The lead-out shaft sealing structure is arranged to bea support structure with the sliding bearing. The sealing performance of the sealing ring can be guaranteed, and simultaneously, the sliding bearing can be supported through the sliding bearing so that the abrasion of an O-shaped sealing ring caused by the extrusion friction of the sealing ring by a box body when the lead-out shaft is rotated and then the sealing performance of the lead-out shaftof the box body is ensured. And, through adopting the sliding bearing, an actual assembling process is convenient and the structure is simple.