Background　The　existing　augmented　reality　(AR)　based　neuronavigation　systems　typically　require　markers　and　additional　tracking　devices　for　model　registration,　which　causes　excessive　preparatory　steps.　Methods　For　fast　and　accurate　intraoperative　navigation,　this　work　proposes　a　marker-less　AR　system　that　tracks　the　head　features　with　the　monocular　camera.　After　the　semi-automatic　initialization　process,　the　feature　points　between　the　captured　image　and　the　pre-loaded　keyframes　are　matched　for　obtaining　correspondences.　The　camera　pose　is　estimated　by　solving　the　Perspective-n-Point　problem.　Results　The　localization　error　of　AR　visualization　on　scalp　and　falx　meningioma　is　0.417　+/-　0.057　and　1.413　+/-　0.282　mm,　respectively.　The　maximum　localization　error　is　less　than　2　mm.　The　AR　system　is　robust　to　occlusions　and　changes　in　viewpoint　and　scale.　Conclusions　We　demonstrate　that　the　developed　system　can　successfully　display　the　augmented　falx　meningioma　with　enough　accuracy　and　provide　guidance　for　neurosurgeons　to　locate　the　tumour　in　brain.