In this paper, we studied theoretically influence of the polarization-state fluctuation on coherent beam combining
(CBC) of fiber lasers. We investigated far-field intensity distribution of the coherently combined fiber laser beams
when the polarization-state varies with time and computed the visibility of the beam profile. The CBC of fiber
laser arrays with time-varying polarization-state was mathematically modeled and the effect of polarization-state
fluctuation was numerically evaluated. The dependence of visibility on the number of fiber laser was computed.
Numerical results showed that the polarization-state fluctuation has a serious influence of coherent beam
combining of fiber lasers in the case of small number, nevertheless, if the number of laser is larger than 10, the
minimal visibility can be as high as more than 80% in the case of random time-varying polarization-state