The pressure vessel of 200 MW low temperature nuclear heating reactor (LTNHR-200) is the main part of primary pressure boundary and its reasonable and reliable structural design is the key point to assure the safe operation of LTNHR-200. The double-shell pressure vessels were designed. LTNHR-200 pressure vessel meets the condition of Leak Before Break and has a relatively low failure probability. Metal containment (outer pressure vessel) has the similar features to LTNHR-200 pressure vessel. There exists no LOCA and core melting with the double vessel. The in-service inspection of the pressure vessel can be simplified greatly because of the safety and structural features of the reactor.