Abstract: The load condition is complicated where a deep-water separator is in service, so its service life is affected by various factors. In order to ensure the safety and reliability of deep-water separators in service, the quantitative relationships between the strength reliability of pressure bearing structure of deep-water separator made of different materials and the design size and material property were investigated further in this paper. By virtue of Monte Carlo method, the series system model of pressure bearing structure was established by taking the wall thickness of pressure bearing structure and the yield strength of material as the stochastic input variables. Then, its accuracy was verified by means of external pressure test. Finally, the stochasticity of design parameters of pressure bearing structure was simulated, and the stress intensity distribution characteristics of pressure bearing structure and the sensitivity and sensitiveness of each parameter to the structure strength reliability of pressure bearing structure were figured out. Case calculation shows that the reliability of pressure bearing structure of deep-water separator in the water of 2 000 m deep is 99.565 3 % and the wall thickness of cylinder is the most important factor affecting the reliability. The research results provide the necessary technological reference for the optimization design of deep-water separators.