In　this　paper,　we　propose　a　robust　and　accurate　indoor　localization　and　tracking　system　using　smartphone　built-in　inertial　measurement　unit　(IMU)　sensors,　WiFi　received　signal　strength　measurements　and　opportunistic　iBeacon　corrections　based　on　particle　filter.　We　utilize　Pedestrian　Dead　Reckoning　(PDR)　approach　which　leverages　smartphone　equipped　accelerometers,　gyroscope　and　magnetometer　to　estimate　the　walking　distance　and　direction　of　user.　The　position　estimated　by　WiFi　fingerprinting　based　approach　is　fused　with　PDR　to　reduce　its　drifting　error.　Since　the　number　of　WiFi　routers　is　usually　limited　for　localization　in　large-scale　indoor　environment,　we　employ　the　emerging　iBeacon　technology　to　occasionally　correct　the　drifting　error　of　PDR　in　poor　WiFi　coverage　area.　Extensive　experiments　have　been　conducted　and　verified　the　superiority　of　the　proposed　system　in　terms　of　localization　accuracy　and　robustness.　©　2017　IEEE.