Abstract: In order to study the effect of aperture reception on the bit error rate of underwater wireless optical communication (UWOC) system under the condition of anisotropic ocean turbulence, Gaussian beam transmission was adopted to pass through an anisotropic ocean turbulence channel under pulse position modulation.The signal was then received though the apertureby the acceptor, the effects of ocean turbulence parameters, transmission distance, average gain of avalanche photodiode (APD), and modulation order on the bit error rate of the system under different receiving aperture and anisotropy factor were numerically simulatedby introducing the anisotropic ocean turbulence structure constant and analyzing the formation principle of scintillation and scintillation index under the condition of anisotropic ocean turbulence. The results show that under the same anisotropy factor and ocean turbulence parameters, the bit error rate performance of the system can be effectively improved by large aperture receiver. The larger the anisotropy factor, the better the system communication performance for the same aperture diameter and ocean turbulence parameters. The bit error rate performance of the system becomes better when the ratios of mean square temperature dissipation rate, temperature, and salinity contribution to the variation of ocean power spectrum are smaller, while the turbulent kinetic energy dissipation rate and kinetic viscosity are larger and the transmission distance is shorter. The performance of system communication is optimal when the APD gain is 100 or 150. The optimal system communication performance is achieved when the modulation order M=8, and the degree of system bit error rate variation is almost saturated when M>64. This study provides a reference for UWOC system platform construction and performance estimation.