The invention discloses a dehumidification system of a high voltage switch cabinet, which comprises a front part dehumidification unit, a rear part dehumidification unit and a power supply appliance (1), wherein the front part dehumidification unit and the rear part dehumidification unit are located in interval positions inside the high voltage switch cabinet (2); the power source terminal of the front part dehumidification unit and the power source terminal of the rear part dehumidification unit are connected with the power supply appliance (1) through power cords; and the water outlet of the front part dehumidification unit and the water outlet of the rear part dehumidification unit are communicated with an outdoor unit (30) of the switch cabinet through a combined water drainage pipe, or the water outlet of the front part dehumidification unit and the water outlet of the rear part dehumidification unit are directly communicated with a cable trench of the high voltage switch cabinet (2). The dehumidification system of the high voltage switch cabinet can avoid the influence of ambient humidity on the high voltage switch cabinet and other switch cabinets, prevent equipment in the cabinet from being damped, and prevent the insulating property of electric apparatus from decreasing.