An　on-line　algorithm　of　fatigue　damage　evaluation　was　proposed　by　modifying　Wang-Brown＇s　method　under　multiaxial　random　loading.　Wang-Brown＇s　method　requires　rearrangement　for　the　strain　history　before　the　counting　process　starts,　which　is　not　suitable　for　on-line　fatigue　damage　evaluation.　So　an　algorithm　based　on　simple　range　counting　for　equivalent　relative　strain　was　presented　first,　and　then　an　on-line　algorithm　was　proposed　by　defining　the　fatigue　damage　in　each　reversal　as　rain-flow　counting　parameter.　The　proposed　on-line　algorithm　does　not　require　any　rearrangement　for　the　strain　history　and　the　fatigue　damage　can　be　evaluated　on-line.　(C)　2010　Elsevier　Ltd.　All　rights　reserved.