Phase-only spatial light modulators are employed to generate controllable wavefront distortion,which is incorporated into a coherent beam combining system to investigate the influence of wavefront distortion in single laser channel on phase control system. Experimental results show that the phase control system is almost not affected in the case of wavefront distortion with small root mean square (RMS) value (i.e.,RMS<π/10). As an increase in the wavefront distortion,the optical phase cannot be totally controlled,residual phase error goes with excursion in the interference patterns exists in the system. When the RMS value of the wavefront distortion is as large as π,the phase control system is in invalidation state and the beamlets cannot be phase locked. Our experimental results present reference for designing and manufacturing high energy laser system based on coherent beam combining.