RMC (Reactor Monte Carlo code) is a new 3D Monte Carlo neutron transport code being developed by Department of Engineering Physics in Tsinghua University. The current version of RMC is a β version. In this paper, based on 2D and 3D benchmark of C5G7, the criticality calculation capacity of RMC was verified. Comparisons were made between the benchmark eigenvalues and those outputs by the RMC code. The RMC-generated eigenvalues were within two standard deviations of the benchmark and MCNP values in all cases. Additionally, the flux was compared pin by pin between MCNP and RMC. The flux tallies generated by RMC were found to be in well agreement with those from MCNP.