Since ‘particle impoverishment’ of the particle filter deteriorates the performance of the single channel blind signal separation based on traditional particle filtering and its huge calculation, a new single channel blind BPSK signal separation algorithm based on particle flow filtering is proposed. Firstly, according to single channel signal of mixing two BPSK signals, a measuring equation and a state equation are built. Secondly, particles are updated through moving the particles in state space which obey the prior distribution to its corresponding posterior distribution, which is different from using resampling to update particles in particle filtering (PF), thereby avoiding the ‘particle impoverishment’ phenomenon caused by re-sampling in PF. Lastly a weak solution based particle flow filter is used to achieve BPSK blind signal separation. Computer simulation results show that compared with particle filtering algorithm the new algorithm has the lower bit error rate and computational complexity.