With the development of underwater optical communication, imaging and sensing, studies of the effect of oceanic turbulence on optical receiving systems have received increasing attention and become a research focus. Until now, the effect of atmosphere turbulence on optical receiving systems have studied widely and in depth, but those in oceanic turbulence have been researched seldom. It is known that the atmosphere turbulence is induced by the temperature fluctuation, while the oceanic turbulence is induced by both the temperature fluctuation and the salinity fluctuation. Thus, the behavior of laser propagation through oceanic turbulence is very different from that in atmosphere turbulence.The paper focuses on the influence of phase disturbance of optical signal caused by oceanic turbulence on optical receiving, including the theoretical modeling of couple efficiency of space optical signal into single-mode fiber received by annular aperture and the variance of angle-of-arrival (AOA) fluctuation received by finite aperture. The research shows that the couple efficiency of single-mode fiber and the variance of angle-of-arrival fluctuation in oceanic turbulence depend on propagation distance, receiving aperture and oceanic turbulence parameter. The results obtained in this paper will be useful for optical receiving systems involving oceanic turbulence channels. © 2021 SPIE