The invention discloses a method for judging the refrigerant leakage of an air-conditioner, comprising following steps of: a. recording the temperature T of an indoor pipe coil before starting a compressor; b. judging whether the compressor is started or not, if so, conducting the next step, if not, returning to the step a; c. judging whether the compressor keeps running for x minutes, if so, conducting the next step, if not, returning to the step b; d. recording the temperature T' of the indoor pipe coil when the compressor keeps running for x minutes and recording indoor temperature Tr simultaneously; e. calculating temperature difference between the temperature T' of the indoor pipe coil when the compressor keeps running for x minutes and the temperature T of the indoor pipe coil before starting the compressor, calculating the temperature difference between the temperature T' of the indoor pipe coil when the compressor keeps running for x minutes and the indoor temperature Tr recorded simultaneously, to see whether the two temperature differences are less than y, if so, conducting step f, if not, then clearing the running time of the compressor and returning to the step b; and f. shutting down to report faults. The method for judging refrigerant leakage in the air-conditioner has high accuracy.