In this work, we propose a negative differential thermal resistance (NDTR) system using a nanoscale sandwiched fluid. Non-equilibrium molecular dynamics simulations and kinetic theory analyses show that the heat flux through the system can be suppressed and even prohibited when the temperature difference across the system becomes sufficiently high. The phenomenon of NDTR is caused by the fluid adsorption on the solid surface at the cold end, which reduces the number density of the free fluid molecules and increases the total thermal resistance of the whole system. The proposed NDTR system provides theoretical insights for the design of certain thermal devices.