The invention discloses a method and device for evaluating the fire safety level of an in-service power cable channel, and the method comprises the steps: obtaining the fire safety characteristics ofan in-service power cable channel, wherein the fire safety characteristics to comprise one or a combination of a cable combustion attribute, a cable operation state, a cable channel environment characteristic, and a cable channel fire protection configuration; for each characteristic influence factor in the fire safety characteristics, obtaining a relative importance value of the influence factors, and establishing an expert judgment matrix; calculating a fuzzy weight vector of each characteristic influence factor, and then carrying out consistency verification on the expert judgment matrix; calculating the target weight of each influence factor after the judgment matrix passes consistency verification; and establishing an evaluation model for the fire safety level of the cable channel according to the target weight so as to evaluate the fire safety level of the cable channel. By applying the embodiment of the invention, quantitative assessment of the fire safety level of the cable channel can be carried out.