Since　digital　forensics　becomes　more　and　more　popular,　more　and　more　attention　has　been　paid　to　the　originality　and　validity　of　data,　and　data　preservation　technology　emerges　as　the　times　require.　However,　the　current　data　preservation　models　and　technologies　are　only　the　combination　of　cryptography　technology,　and　there　is　a　risk　of　being　attacked　and　cracked.　And　in　the　process　of　data　preservation,　human　participation　is　also　needed,　which　may　lead　to　data　tampering.　To　solve　problems　given,　this　paper　presents　a　data　preservation　model　based　on　blockchain　and　multidimensional　hash.　With　the　decentralization　and　smart　contract　characteristics　of　blockchain,　data　can　be　automatically　preserved　without　human　participation　to　form　a　branch　chain　of　custody　in　the　unit　of　case,　and　blockchain　has　good　antiattack　performance,　which　is　the　so-called　51%　attack.　Meanwhile,　in　order　to　solve　the　problem　of　data　confusion　and　hard　to　query　caused　by　the　excessive　number　of　cases,　hash,　cryptography,　and　timestamps　are　used　to　form　a　serialized　main　chain　of　custody.　Because　of　the　confliction　problem　of　hash　and　judicial　trial　needs　to　absolutely　guarantee　the　authenticity　and　validity　of　data,　multidimensional　hash　is　used　to　replace　regular　hash.　In　this　way,　the　data　preservation　becomes　an　automatic,　nonhuman-interventional　process.　Experiments　have　been　carried　out　to　show　the　security　and　effectiveness　of　the　proposed　model.　©　2021　Gongzheng　Liu　et　al.