The　fusion　neutron　penumbral　imaging　system　Monte　Carlo　model　was　established.　The　transfer　functions　of　the　two　discrete　units　in　the　neutron　source　were　obtained　in　two　situations:　Imaging　in　geometrical　near-optical　and　real　situation.　The　spatial　resolutions　of　the　imaging　system　in　two　situations　were　evaluated　and　compared.　The　penumbral　images　of　four　units　in　the　source　were　obtained　by　means　of　2-dimensional　(2D)　convolution　and　Monte　Carlo　simulation.　The　penumbral　images　were　reconstructed　with　the　same　method　of　filter.　The　same　results　were　confirmed.　The　encoding　essence　of　penumbral　imaging　was　revealed.　With　MCNP(Monte　Carlo　N-particle)　simulation,　the　neutron　penumbral　images　of　the　large　area　source　(200　mu　mx200　mu　m)　on　scintillation　fiber　array　were　obtained.　The　improved　Wiener　filter　method　was　used　to　reconstruct　the　penumbral　image　and　the　source　image　was　obtained.　The　results　agree　with　the　preset　neutron　source　image.　The　feasibility　of　the　neutron　imaging　system　was　verified.