A multi-channel audio signal decoding method and device is provided. The multi-channel audio signal decoding method includes receiving a first multi-channel audio signal; performing a first decoding procedure on the first multi-channel audio signal to generate a second multi-channel audio signal; performing a second decoding procedure on a first single-channel audio data of the second multi-channel audio signal to generate a first single-channel audio signal when the first single-channel audio data belongs to a first classification; and performing a third decoding procedure on a second single-channel audio data of the second multi-channel audio signal to generate a second single-channel audio signal when the second single-channel audio data belongs to a second classification. The number of instructions of the third decoding procedure is less than that of the second decoding procedure.