This　paper　presented　a　real-time　failure　predictive　system　of　the　elevator　brake.　Through　inspecting　the　running　state　of　the　coil　by　a　high　precision　long　range　laser　triangulation　non-contact　measurement　sensor,　the　displacement　curve　of　the　coil　is　gathered　without　interfering　the　original　system.　By　analyzing　the　displacement　data　using　the　diagnostic　algorithm,　the　hidden　danger　of　the　brake　system　can　be　discovered　in　time　and　thus　avoid　the　according　accident.