Metal　halide　materials　have　attracted　widespread　attention　due　to　their　excellent　photophysical　properties,　particularly　in　the　field　of　radiation　detection.　However,　their　practical　applications　are　often　restricted　due　to　their　inherent　crystalline　nature,　which　often　leads　to　brittleness　and　poor　processability.　Herein,　we　proposed　a　novel　strategy　to　prepare　polymerized　manganese(II)　halides　(MnP)　as　a　new　class　of　plastic　scintillator.　The　self-adaptive　host-guest　cationic　motifs　provided　high　conformational　flexibility　and　numerous　hydrogen　bonding　sites,　which　facilitated　the　polymerization　process.　The　MnP　films　exhibited　superior　processability　and　high　transmittance　(＞90%).　By　tuning　the　guest　cations,　the　crystalline　manganese(II)　halides　achieved　a　near　unity　photoluminescence　quantum　yield　(PLQY).　The　MnP　films　and　the　crystalline　manganese(II)　halides　showcased　outstanding　X-ray　scintillation　performances,　demonstrating　a　detection　limit　of　0.012　mu　Gy(air)　s(-1)　and　a　high　spatial　resolution　of　13.06　lp　mm(-1).　This　approach　is　expected　to　provide　an　alternative　to　advancing　the　development　of　high-performance　plastic　scintillators.