Abstract: The offshore nuclear energy platform, characterized by low operating costs, reliable energy supply, and environmental friendliness, can provide stable and reliable energy for the development of offshore oil and gas resources and the livelihood support of personnel. The offshore fixed lead-cooled reactor platform, addressing the demand for stable energy supply in China's maritime regions, aims to propose a conceptual design for a reactor with an electrical power output of 20 MW, a service life of 40 years, and no need for replacement of materials throughout its entire lifespan. This paper uses the CAR-3600 benchmark and validates the applicability of the burnup module of the open-source Monte Carlo program OpenMC in a lead-cooled fast reactor. A comparison of the calculation results for the offshore fixed lead-cooled reactor core between the OpenMC and MCNP programs is conducted, analyzing the differences in results obtained using different nuclear databases in the OpenMC program and exploring possible reasons for these differences. The research results indicate that the burnup module of the OpenMC program is applicable in fast reactors. The calculation results of OpenMC and MCNP programs are close, and a comparative validation of the design scheme for the offshore fixed lead-cooled reactor is carried out using different simulation software. The simulation also reveals that due to differences in capture cross-sections of ²³⁵U and ²³⁸U, the reactivity fluctuations obtained from the ENDF/B-VIII.0 library and the JEFF-3.3 library are larger than the design target of 1\; \, requiring further optimization of the scheme to reduce burnup reactivity fluctuations.