To　improve　the　control　performance　and　robustness　of　fractional　order　PID　(FOPID)　controller　for　the　uncertainty　model,　a　tuning　method　for　FOPID　controller　based　on　probabilistic　robustness　is　proposed　in　this　paper.　Based　on　the　Monte　Carlo　simulation,　a　probabilistic　robustness　index　is　formulated　to　represent　the　controller　sensitivity　to　the　uncertainty　model.　Stability　boundaries　of　FOPID　is　depicted　to　provide　the　search　space,　in　which　the　optimal　group　of　parameters　are　selected　based　on　the　probabilistic　robustness　index.　The　procedure　of　the　proposed　method　is　designed　to　obtain　the　optimal　controller　parameters　for　the　uncertainty　model.　Numerical　examples　are　performed　to　verify　the　efficacy　of　the　proposed　method,　and　simulation　results　show　that　the　proposed　method　has　better　performance,　stronger　robustness　and　ability　of　handling　uncertainties.　©　2018