Abstract: BEAVRS is an international benchmark model based on the commercial PWR reactor with full-core meticulous modeling from MIT, and it has detailed measurement data. BEAVRS is a large 3D reactor benchmark for verification consisted of a variety of enrichment fuels and control rod assemblies. In this paper, cosRMC(a Monte Carlo code independently developed by China) is adopted in the detailed modeling of BEAVRS benchmark to calculate the critical eigenvalues, full reactor power distribution and the control rod worth with different control rod assenmblies inserted in the hot zero power(HZP) status. The results are compared with those by the internationally renowned programs MCNP, OpenMC and MC21. In the HZP status, the critical eigenvalue error between cosRMC and MCNP is just 7.1 pcm; the eigenvalues with different control rod assemblies inserted are calculated and the error is less than 0.74% compared with the theoretical error 1.000, and the difference between the calculated control rod worth and the measured value is less than 100 pcm, and the calculation accuracy agrees well with that of similar software; also the calculated full reactor power distribution is compared with the measured value and the reasons of error are analysed. The feasibility and accuracy of cosRMC in the complex core meticulous modeling are verified preliminarily, which lays a foundation for future applications and improvement.