The invention relates to a lead icing thickness monitoring method. The method comprises the following steps that: step S01, an icing thickness b is calculated according to a lead inclination angle; step S02, an icing thickness b2 is calculated according to a video picture; step S03, the icing thickness b and the icing thickness b2 are compared; if the difference value delta b exceeds a certain range, the video picture is captured again on the premise that the video picture maintains a predetermined definition and a lead icing thickness value b2 is calculated again according to the step S02; and if the definition of the video picture is lower than the predetermined definition, the calculation value of the step S01 is used as a final result; step S04, the recalculated thickness value b2 is compared with the b again; and if the difference value is still exceeds a predetermined range, a lead icing density value b' and an ice load value lambda' are corrected in a given range; and step S05, a lead tension calculation value sigma is corrected based on the original lead inclination value and the corrected lead ice load value. According to the invention, the lead icing thickness can be determined accurately; and a lead tension calculation value that is caused by a measurement error and an environment factor can be corrected.