The invention discloses a pressurized-water nuclear reactor structure. The structure comprises an integrated reactor top, an actuating mechanism, a pressure vessel, reactor internals and a heat-insulating component, wherein the integrated reactor top is connected with a top cover of the pressure vessel, the heat-insulating component is arranged on the external surface of the pressure vessel, the reactor internals are hung to a supporting step of the pressure vessel, and the actuating mechanism is mounted on the top cover of the pressure vessel. According to the pressurized-water nuclear reactor structure, a neutron flux measurement detector, a temperature measurement detector and a water level measurement detector can be led out of a reactor through a reactor internal measurement guide structure and a pressure vessel top penetrating piece which are located in an upper closure head of the pressure vessel, so that the increase of number of reactor internal measurement tube holders on the top cover is avoided; the requirements on water level measurement can be met; the flow of a coolant entering a reactor core is distributed reasonably; the technical effect of rapidly cooling the exterior of the pressure vessel of the reactor can also be achieved by a heat insulating layer.