We propose a parallel relaying coherent orthogonal frequency division multiplexing free-space optical (FSO) communication system model with amplify-and-forward channel-state-information-assisted relaying in an M distribution. Considering the combined effects of path loss, pointing error, and atmospheric turbulence, the closed-form expression of moment generating function, probability density function, and cumulative distribution function of the upper limit of equivalent signal-to-noise ratio are derived. Furthermore, the Meijer G closed-form expressions for outage probability and symbol error rate (SER) over M aggregated channel are obtained. The influences of turbulence intensity, the number of parallel paths, normalized beam bandwidth, normalized jitter error, and pointing error on the outage probability and SER of the proposed FSO system are analyzed by simulation. Simulation results indicate that controlling the normalized beam width to a moderate range and reducing the normalized jitter error can reduce the outage probability and improve system reliability. After the pointing error exceeds 7, the SER decline tends to be flat, which provides a theoretical reference for the precision of the pointing technology, the selection of the optical antenna transmission aperture and the receiver sensitivity index in engineering design.