The integration of neutronics and thermal-hydraulic in multi-physics coupling analysis plays a crucial role in achieving high-fidelity simulations of nuclear reactor cores. In the current work, the neutronics and thermal hydraulic Multi-physics coupling methodology was proposed for the plate-type fuel assemblies inside Material Test Reactor cores. The coupling technique is based on the two-way and external coupling paradigms and accomplished using Monte Carlo Reactor analysis and subchannel thermal-hydraulic codes. The coupling interface was developed using Python and Modern Fortran programming languages. The three-dimensional reactor physics modelling was developed using MCNP6 code while the one-dimensional thermal-hydraulic model was developed using PARET/ANL v2.1 for a typical MTR plate-type fuel reactor. Subsequently, the coupling analysis was conducted using the developed integrated code system. The simulation results from the coupling and non-coupling methods were compared to validate the feasibility of the coupling approach, revealing that the proposed coupling method offers greater accuracy compared to the traditional approach.