In　order　to　prepare　ultra　high　toughness　cementitious　composites　(UHTCC),　influence　of　different　fibers　and　proportion　on　the　mechanical　properties　of　cementitious　composites　were　discussed　based　on　the　compressive　test,　the　flexural　test　and　the　direct　tensile　test.　Research　results　show　that　organic　fiber　decrease　the　compressive　strength　of　UHTCC,　however,　the　flexural　strength　increases.　According　to　the　mechanic　properties　and　the　cost　of　materials　comprehensive　consideration,　it　is　suggested　that　the　optimal　dosage　of　fiber　is　2%;　the　most　significant　of　tensile　strain　hardening　is　Japanese　polyving　akohol　(PVA)　fiber　reinforced　cementitious　composites,　the　following　is　the　domestic　PVA　fiber,　and　there　is　no　strain　hardening　phenomenon　in　the　domestic　polypropylene　(PP)　fiber　and　polyethylene　(PE)　fiber　under　the　direct　tension.　©　2017,　Editorial　Board　of　Journal　of　Huazhong　University　of　Science　and　Technology.　All　right　reserved.