The invention provides a reactor with a passive reactor core residual heat removal function. The reactor comprises a fully-closed containment, a reactor vessel and a high-temperature-resistant concrete layer are arranged in the containment, the high-temperature-resistant concrete layer is poured with reinforced ceramic grain concrete, at least one first outer side wall connected with the inner wall of the containment and at least one second outer side wall connected with the outer wall of the reactor vessel are formed on the high-temperature-resistant concrete layer, and a cooling circulation system for cooling the outer wall of the containment is arranged on the outside of the containment. According to the reactor, the fully-closed high-temperature-resistant concrete layer is formed by the reinforced ceramic grain concrete, local loads of a concrete structure are effectively reduced, shock resistance of the reactor is improved, overpressure risks in the containment are avoided by the aid of a solid heat conducting mode, the installation space of a system is saved, and construction cost is reduced.