Compared with the conventional training symbols-based channel equalization method, the blind channel equalization method based on the independent component analysis (ICA) improves considerably the spectral efficiency of the polarization-division-multiplexing coherent-optical orthogonal-frequency-division-multiplexing (PDM- CO- OFDM) systems. However, the blind channel estimation requires the computations of the channel frequency response on subcarrier basis and needs dozens of iterations to converge. To reduce its computational complexity, on the basis of the channel equalization using ICA, a blind channel equalization method is proposed. It is performed by using ICA with adaptive variable step, and the separation step method enhances the convergence rate of the iterative algorithm greatly. For 100 Gb/s PDM-CO-OFDM with 16 quadrature amplitude modulation (16 QAM), it is proved by the simulation results that its convergence rate improves more than five times, compared with the channel equation method by using ICA with fixed iterative step. This method can be used to realize high efficiency channel equalization in the future high speed PDM-CO-OFDM system receivers.