The present invention discloses a method and apparatus for evaluating the moisture resistance of the air intake filter of a gas turbine. According to the method, humidified air is made to pass through the intake air filter, so that resistance delta P of the intake air filter is measured; the resistance delta P is modified into delta P 1.203 according to a formula 1; the intake air filter is graded according to the change value of the delta P 1.203 in a certain time or time for the delta P 1.203 to reach a certain numerical value; the moisture resistance of the air intake filter is evaluated. Such method and apparatus provided by the invention are put forward for the first time both at home and abroad; and on the basis of the filter itself, the process of the change of the filter with the time under the stress of high-humidity air is quantified, and therefore, the moisture resistance of the air intake filter is evaluated. The method is suitable for the evaluation of general ventilation filters. The method is of great significance to solving of a moisture plugging problem faced by the intake air filter of the gas turbine and the regulation of air filter manufacturers.