Audio system and related method integrated with ultrasound communication functionality are provided. A communication transmitting device of proposed invention modulates a communication signal of communication functionality to a high-frequency sound and transmits the high-frequency sound by an ordinary audio transmitter. A communication receiving device of proposed invention receives the high-frequency sound with an ordinary audio receiver and demodulates it to retrieve the communication signal, and then the communication device can use the communication signal. The proposed audio sound transmitter/receiver can be implemented using low-cost audio speaker/microphone, such that a cost for implementing communication functionality can be reduced.