The invention discloses a unidirectional pressure relief valve device for a radioactive contamination ventilation protective suit. The unidirectional pressure relief valve device for the radioactive contamination ventilation protective suit comprises a pair of bottom thin film plastic valve plate and outer thin film plastic valve plate which have rigidity hardness and self-absorption property textures. The bottom thin film plastic valve plate and the outer thin film plastic valve plate are oppositely arranged, and a gap for air circulation is arranged between the bottom thin film plastic valveplate and the outer thin film plastic valve plate. A through hole communicating with the gap is formed in the bottom thin film plastic valve plate. According to the unidirectional pressure relief valve device for the radioactive contamination ventilation protective suit, the absorption characteristic of functional plastic materials is fully utilized so that the structure of the unidirectional exhaust valve becomes small and compact, and the use of springs is eliminated; and unidirectional exhausting is achieved, and meanwhile, the sealing property under a closed circumstance is good, and theproblem of radioactive aerosol back-flow does not occur.