The present invention provides an asymmetric EEG-based coding and decoding methods for BCIs, the BCI system includes an evoked stimulus module, an acquisition module and an EEG signal data set including a training set Xk and a testing sample Y, and an EEG signal decoding module; the evoked stimulus module sends a hybrid coding visual stimulus to subjects to evoke a specific EEG signal as required; the acquisition module obtains data information by amplifying and filtering the EEG signal so as to constitute EEG signal module; the decoding module coverts the data information into an instruction set for outputting the coding method of the present invention uses asymmetric characteristics of brain electrophysiological activity response to stimulus, combines with coding strategies such as SDMA, CDMA, FDMA and phase division multiple access coding.