Aiming at the problem that the fixed threshold decision scheme leads to the deterioration of the performance of the underwater wireless optical communication system in the turbulent channel environment, a dynamic threshold decision scheme is proposed. Based on the slow fading characteristic of the underwater turbulent channel, the data is sent by frame at the sending end, and the decision threshold is updated every frame at the receiving end according to the amplitude of the leading code of the receiving frame. This paper uses the Monte Carlo method and the Gamma-Gamma turbulence channel model to simulate the underwater wireless optical communication system. The simulation results show that in the case of weak turbulence channel environment and when the system bit error rate is 10-6, the dynamic threshold decision scheme improves the bit error performance by 5.4 dB compared with the fixed threshold decision scheme. In the case of medium and strong turbulence channel environment,the dynamic threshold decision scheme can effectively suppress the occurrence of bit error rate threshold phenomenon.