Experimental　research　was　carried　out　to　evaluate　the　comparative　fracture　performance　of　random　steel　fiber-reinforced　composite　(SFRC)　and　aligned　steel　fiber-reinforced　composite　(ASFRC).　The　desired　direction　of　steel　fiber　in　the　fresh　cementitious　mortar　was　achieved　by　the　electromagnetic　field.　Three-point　bending　tests　were　conducted　on　geometrically　similar　notched　beam　specimens.　Various　dimensions　and　steel　fiber　contents　by　volume　V-f　were　considered　to　study　fracture　performance　and　investigate　the　size　effect.　The　fracture　parameters　were　analyzed　by　nonlinear　fracture　models,　namely　the　size　effect　model　(SEM),　work　of　fracture　method　(WFM),　and　double-K　fracture　criterion　(DKFC).　Initial　fracture　energy,　critical　fracture　toughness　K-IC,　length　of　fracture　process　zone,　and　critical　tip　opening　displacement　from　SEM,　total　fracture　energy,　and　characteristic　length　from　WFM　was　studied　for　SFRC　and　ASFRC.　The　initial　cracking　load　was　detected　with　strain　gages　to　evaluate　initial　fracture　toughness　K-IC(ini).　Unstable　fracture　toughness　K-IC(un)　from　DKFC　with　special　emphasis　on　size　effect　was　obtained.　The　results　show　that　the　rise　of　specimen　depth　has　no　considerable　effect　on　the　K-IC(un)　while　the　size　effect　of　K-IC(ini)　is　not　significant.　As　the　increment　of　V-f,　both　the　K-IC(ini)　and　K-IC(un)　show　a　linear　ascending　trend　and　both　of　them　are　greater　for　ASFRC　than　those　of　SFRC　specimens.　It　is　found　that　there　exists　a　strong　correlation　between　the　fracture　toughness　measured　by　DKFC　and　SEM　(K-IC　from　SEM　similar　or　equal　to　K-IC(un)　from　DKFC).　Generally,　the　fracture　performance　of　ASFRC　relative　to　that　of　random　SFRC　is　improved　by　more　than　80%.　(C)　2021　Elsevier　Ltd.　All　rights　reserved.