The invention discloses a lead equivalent icing thickness monitoring device and method based on an ice medium capacitance effect. The device comprises a control unit, a power taking unit and a high-frequency excitation power supply conversion unit which are connected through a lead; the high-frequency excitation power supply conversion unit is connected with a monitoring unit through a lead; and the monitoring unit is connected with the control unit through a lead. The technical problem that in the prior art, the icing thickness and state of a power transmission line lead are not accurately monitored is solved.