A brain signal-based control method and control device, and a man-machine interaction device. The method comprises: periodically obtaining electroencephalography signals and brain oxygen signals within a target period of time, and respectively generating a brain waveform curve and a brain oxygen waveform curve which represent changes of an electroencephalography signal and of a brain oxygen signal within the target period of time (S101); determining whether the brain waveform curve and the brain oxygen waveform curve meet conditions for controlling a controlled device to perform a target operation (S102); and controlling the controlled device to perform the target operation when the brain waveform curve and the brain oxygen waveform curve meet the conditions (S103). Compared with the mode for controlling the controlled device on the basis of the electroencephalography signal only in the prior art, according to the control method, the electroencephalography signal and the brain oxygen signal are simultaneously detected, the brain waveform curve and the brain oxygen waveform curve are generated, and whether the brain waveform curve and the brain oxygen waveform curve meet the conditions for controlling the controlled device to perform the target operation is determined, so that a false operation caused by situations such as hopping of single piece of data can be avoided, and control accuracy is improved.