A random phase screen model of ocean turbulence is proposed. Based on the fluctuating spectrum of ocean refractive index, the influence of the refractive index fluctuation of ocean medium on the transmitted beam caused by oceanic turbulence is equivalent to the influence of random phase screens on the beam with the power spectrum inversion method. The validity of the proposed model is testified by the phase structure function and the transmission characteristic of orbital angular momentum beam in ocean turbulence. Results show that the phase structure function values calculated by the random phase screen model are coincident with the theoretical results when the offset of beam refractive index is small. At the same time, the transmission characteristics of the orbital angular momentum beam obtained by the random phase screen model are also consistent with the theoretical analysis results.