In order to study the influence of plastic drainage board pre-pressure on settlement, take the deep China channel Lingdingyang bridge west anchor artificial island project as an example, use three-dimensional finite element numerical simulation and Monte Carlo method to analyze the settlement of the island, to explore the pre-pressure treatment of plastic drainage board after the rule of change of soft ground consolidation settlement and the reliability of settlement after work. The results of the study show that: the plastic drainage board method using the principle of consolidation equivalence can effectively simulate the changes of soft foundation consolidation and settlement; with the decrease of the spacing of the plastic drainage board or the increase of the water throughput, the rate of consolidation and settlement of the blowing soft foundation in the pre-compression period will increase; the change of the spacing of the plastic drainage board or the amount of water throughput has a small effect on the final amount of consolidation and settlement of the soft foundation; the use of the Monte Carlo method of the reliability of the soft foundation settlement after work. The reliability of post-construction settlement of soft foundation by Monte Carlo method is analyzed, and it is found that when the coefficient of variation of infiltration rate is greater than 0.5, the prediction of post-construction settlement is more affected. The conclusion can provide reference for related projects.