The　paper　proposes　a　novel　geometric　error　identification　methodology　for　the　tilting　head　of　five-axis　machine　tools　using　double　ball　bar(DBB).　Firstly,　based　on　the　motion　condition　of　the　tilting　head　of　five-axis　machine　tools,　three　measurement　patterns　in　Y　direction,　X　direction　and　Z　direction　are　proposed　respectively.　Then,　the　relative　displacement　equations　of　two　balls　of　DBB　in　three　measurement　patterns　are　established　respectively　on　the　basis　of　homogeneous　transform　matrix　(HTM)　and　multi-body　system　(MBS)　theory.　Finally,　the　geometric　error　parameters　of　the　tilting　head　are　identified　totally.　The　presented　method　is　universal　and　provides　a　reference　for　the　error　identification　for　the　tilting　head　of　five-axis　machine　tools.