The received laser beam in a free-space optical communication using fiber-optic components system must be coupled into a single-mode fiber. However, propagation through atmospheric turbulence degrades the fiber-coupling efficiency. Single-mode fiber coupling efficiency of expression as a function of atmospheric turbulence parameters is extended to the oblique propagation scenarios, and the coupling efficiency as functions of turbulence intensity, transmission distance and zenith angle is simulated. To compensate for turbulence effects and improve fiber coupling efficiency, this paper use a novel model-free blind optimization wavefront correction with random parallel gradient optimization algorithm to control deformable mirrors and couple the corrected light into the single-mode fiber, so single-mode fiber coupling efficiency is optimized. The results show that single-mode fiber coupling efficiency is significantly improved.