Abstract: On the basis of a blind separation structure with low complexity, an efficient blind separation algorithm based on nonlinear filtering is proposed for asymmetric PCMA (Paired Carrier Multiple Access), and the strong signal demodulation bit error rate theorists under the influence of the weak signals is studied in-depth. Firstly, the mixed signals are synchronized as the strong signal, and the demodulation bit error rate of the strong signal is reduced by subtracting the prediction waveform of the weak signals from the mixed signals, while the nonlinear filtering is introduced for the weak signals waveform prediction which utilizing the predictability of the waveform of the weak signals. The simulation results show that, compared with the hard decision of the mixed signals, the demodulation error performance of the strong signal has a great improvement after nonlinear filtering.