Abstract: The pressured cabin of the manned spacecraft provides the places of working and living for astronauts. It is critical to analyze the organ dose in the pressured cabin, in order to predict quantitatively the hazard on astronauts due to the space ionizing radiation. This paper discusses the technical process of the dose analysis and the method of the three-dimensional simulation of the organ dose. For a medium-term-resident manned spacecraft, the magnitude distribution of the organ doss in the pressured cabin is simulated. The simulation results can be used for the systematical design of radiation protection.