A method for modulation mode self-adaptation in communication via an audio interface, comprising: modulating by a first device first audio data to be sent using at least two modulation modes supported by the first device respectively to generate first audio data frame streams in the at least two modulation modes; splicing by the first device the first audio data frame streams in the at least two modulation modes into a first audio data stream; sending the first audio data stream to a second device via an audio interface of the first device; demodulating by the second device the first audio data stream to obtain modulation modes correctly received by the second device and supported by the first device; modulating by the second device second audio data to be sent using at least two modulation modes supported by the second device to generate second audio data frame streams in the at least two modulation modes, wherein the second audio data comprise the modulation modes correctly received by the second device and supported by the first device; splicing by the second device the second audio data frame streams in the at least two modulation modes into a second audio data stream, and sending the second audio data stream to the first device via an audio interface of the second device; demodulating by the first device the second audio data stream to obtain modulation modes correctly received by the first device and supported by the second device and to obtain modulation modes correctly received by the second device and supported by the first device; and selecting by the first device an optimal modulation mode used in the second device from the modulation modes correctly received by the second device and supported by the first device, and selecting by the first device an optimal modulation mode used in the first device from the modulation modes correctly received by the first device and supported by the second device, according to a predetermined rule. modulating by a first device first audio data to be sent using at least two modulation modes supported by the first device respectively to generate first audio data frame streams in the at least two modulation modes; splicing by the first device the first audio data frame streams in the at least two modulation modes into a first audio data stream; sending the first audio data stream to a second device via an audio interface of the first device; demodulating by the second device the first audio data stream to obtain modulation modes correctly received by the second device and supported by the first device; modulating by the second device second audio data to be sent using at least two modulation modes supported by the second device to generate second audio data frame streams in the at least two modulation modes, wherein the second audio data comprise the modulation modes correctly received by the second device and supported by the first device; splicing by the second device the second audio data frame streams in the at least two modulation modes into a second audio data stream, and sending the second audio data stream to the first device via an audio interface of the second device; demodulating by the first device the second audio data stream to obtain modulation modes correctly received by the first device and supported by the second device and to obtain modulation modes correctly received by the second device and supported by the first device; and selecting by the first device an optimal modulation mode used in the second device from the modulation modes correctly received by the second device and supported by the first device, and selecting by the first device an optimal modulation mode used in the first device from the modulation modes correctly received by the first device and supported by the second device, according to a predetermined rule.