An audio signal transmission system includes a first device and a second device. The first device transmits audio signals to the second device for the second device to process the audio signals and recognize data in the audio signals. After converting a piece of information read by the first device into digital data, the first device performs data state conversion algorithm to generate a time-based byte sequence, modulates the byte sequence to a set of audio signals, and transmits the set of audio signals. When receiving the set of audio signals, the second device filters and demodulates the set of audio signals to acquire the byte sequence, and converts the byte sequence into readable information. As the byte sequence has time-based characteristics, multiple independent pulse signals can be constantly provided to enhance audio signal recognition and ensure accuracy and stability of the audio signal transmission system.