To　minimize　the　size　and　weight　of　the　vehicle-mounted　accelerator-driven　D-D　neutron　source,　optimization　of　compact　and　lightweight　radiation　shielding　material　for　the　fast　neutrons　was　carried　out,　which　employed　genetic　algorithms　and　the　MCNP　code.　Based　on　this　method,　a　series　of　material　samples　were　designed　and　the　shielding　performance　was　compared　with　that　of　traditional　materials　such　as　PB202,　PE-30%B,　M-L1　and　M-L2　for　the　D-D　neutron　by　MCNP.　To　compare　the　shielding　performance　conveniently,　both　of　the　needed　volume　and　weight　were　compared　while　assuming　the　shielding　as　a　coaxial　tapered　cylinder.　The　results　show　that　the　SDGa　can　satisfy　the　requirements　of　lightweight　and　compact　simultaneously.　At　the　same　time,　the　activation　gamma　dose　rates　of　SDG3　and　SDG3*　after　1　000　h　irradiation　were　evaluated,　and　the　results　show　that　the　activation　can　be　neglected.　©　2018,　Editorial　Board　of　Atomic　Energy　Science　and　Technology.　All　right　reserved.