The invention relates to a characteristic extraction method of motor imagery electroencephalogram signals. According to the method, firstly, the collected electroencephalogram signals are preprocessed, then EMD is performed on all leads of signals to obtain multi-order IMF signals, then the IMF signals which are identical in number of orders are selected as new signals, a spatial filter is obtained through a CSP algorithm, characteristics of the electroencephalogram signals are extracted and input into a classifier for classification, the optimal value of parameters in the EMD and CSP is selected according to the classification accuracy rate, and finally the electroencephalogram characteristics under the optimal parameter are obtained. Based on the EMD and CSP, characteristic extraction is performed on the motor imagery electroencephalogram signals, the signals can be decomposed into the multiple IMF signals in a self-adaptation mode according to characteristics of the electroencephalogram signals of different persons, characteristic extraction can be performed on the electroencephalogram signals only by few electrodes, and the classification accuracy rate of the electroencephalogram signals is increased to a greater degree.