The　integrated　substation　automation　system　(ISAS)　based　on　IEC-61850　is　the　development　direction　of　the　intelligent　substation.　Currently,　the　reliability　research　of　the　ISAS　rarely　involves　the　quantitative　influence　of　human　factors.　Therefore,　a　risk　assessment　technique　of　ISAS　considering　human　reliability　is　proposed.　The　technique　is　based　on　Human　Factors　Analysis　and　Classification　System　framework,　Fuzzy　Fault　Tree　Analysis　methodology,　and　Functional　Decomposition　method.　Then,　it＇s　applied　to　the　integrated　anti-misoperation　system　in　ISAS.　The　system＇s　reliability　considering　human　error　is　quantitatively　evaluated　through　a　series　of　studies.　The　results　show　that　a　quantitative　method　is　valuable　in　assessing　the　reliability　of　ISAS.　The　main　contributions　of　this　paper　are:　1)　to　give　explicit　formulas　for　risk　assessment　of　ISAS,　which　objectively　describes　the　system　risk　and　provides　risk　prompts　for　dispatch　operators;　2)　to　intuitively　reflect　how　the　reliability　attributes　of　the　system＇s　equipment　and　network　interfere　with　the　reliability　of　the　system;　3)　to　prove　that　human　errors　will　seriously　affect　the　risk　level　of　the　system.　As　the　rate　of　human　error　increases,　the　risk　level　of　the　system　rises　until　it　collapses.　©　1986-2012　IEEE.