Research on the mechanical properties of variable diameter Independent pile under the combined action of wind, wave and flow is carried out. Take a variable diameter Independent pile in CB11F platform of Chengdao oilfield for example, simulative analysis is performed using the finite element software ANSYS , considering the influence for some factors to structure response, that is environmental load, soil conditions and variable diameter position. The variable diameter part of the smooth gradient cone is simplified reasonably, getting the top of the displacement and the whole body stress of variable diameter pile under wave and flow actions, comparing with the result of non-variable diameter pile, the results show that the displacement and stress of variable diameter pile decrease more than 20%, the measure adopted in this paper about decreasing the displacement of independent pile and the stress of whole body is validated.