Compared　with　cylindrical　worms,　planar　double　enveloping　hourglass　worms　(TP　worms)　have　plenty　of　advantages.　The　measurement　of　TP　worms　is　a　key　problem　limiting　the　application　of　the　worms.　With　regards　to　this,　we　present　a　measurement　method　for　TP　worms　and　develop　a　special　worm　measuring　machine　which　can　achieve　the　purpose　of　measuring　geometric　deviations.　The　working　principle　and　constitution　of　the　machine　are　introduced,　and　the　principle　of　the　measurement　based　on　the　mathematical　model　of　each　geometric　deviation　is　explained　in　detail.　An　example　of　helix　deviation　measurement　shows　the　whole　process　of　the　measurement.