A blind inter-carrier interference (ICI) phase noise compensation algorithm, which can solve the problem of symbol decision error effectively, is proposed based on the large linewidth coherent optical orthogonal frequency division multiplexing (CO-OFDM) system. Before using the proposed algorithm, we use the non-iterative blind (IFB) algorithm to compensate phase noise of common phase error (CPE). The proposed algorithm uses the cost function which is with simple form, so the computational complexity reduces significantly. The ICI phase noise compensation algorithm includes coarse ICI phase noise compensation and fine ICI phase noise compensation. Firstly, the average-power blind (Avg-BL) algorithm is implemented in the coarse ICI phase noise compensation, and then the common phase error compensation (CPEC) algorithm is implemented in the fine ICI phase noise compensation. A decision process will be performed by CPEC algorithm for the frequency-domain signals after the coarse ICI phase noise compensation. Every received OFDM symbol is separated into several sub-symbols in time-domain, and the approximate average value of phase noise of every sub-symbol is calculated. The sign decision error propagation problem in CPEC algorithm is solved when we use the Avg-BL algorithm. When the number of sub-symbols separated from OFDM symbol in time-domain is large, the CPEC algorithm can achieve the desired compensation performance for ICI phase noise. For the 50 Gbit/s CO-OFDM system with 100 km transmission distance, the numerical simulation is performed. The simulation results show that, compared with the other phase noise compensation algorithms, such as the Avg-BL algorithm and the CPEC algorithm, the proposed algorithm has good phase noise compensation performance with high spectral efficiency. With the suitable number of OFDM sub-symbols in time-domain, the proposed algorithm can obtain better compensation performance, and its complexity does not increase significantly.