The invention relates to a method for estimating an accumulation amount of electric heat degradation of a power cable with consideration of a random process. The method comprises the steps: determination of daily load of the power cable, estimation of temperature of the power cable conductor, determination of electric heat service life model of the power cable and estimation of the degradation and accumulation amount of the power cable. The determination of daily load of the power cable comprises acquiring a load curve of the power cable in a step-like changing manner and acquiring current in the power cable; the estimation of conductor temperature of the power cable comprises acquiring temperature distribution of the power cable conductor; the determination of electric heat service life model of the power cable comprises evaluating the service life of the power cable in the electric stress, the heat stress and the synergistic condition; the estimation of the degradation and accumulation amount of the power cable comprises solving an accumulation amount of degradation of the power cable within a certain period of time. By adopting the method, predicting accuracy of service life of the power cable can be improved.