To　measure　complex　geometries　without　nominal　mathematics　models,　a　＇form-free　measurement　mode＇　is　introduced,　and　its　basic　requirements　for　measuring　machine　are　analyzed.　A　fixed　column　structure　coordinate　measuring　machine　with　high　accuracy　and　efficiency　was　designed　based　on　the　novel　mode.　The　machine　is　driven　by　linear　motors,　and　high　accuracy　gratings　are　used　as　measurement　devices.　To　decrease　the　influence　of　workpiece　weight,　a　closed　aerostatic　bearing　with　vacuum　preload　and　an　H　style　two　dimensional　co-planar　structure　are　designed.　A　pneumatic　cylinder　balanced　axis　Z　assembly　with　brake　function　is　designed,　and　a　vibration　isolation　assembly　is　also　designed.　The　measurement　span　of　the　machine　is　300　mm×300　mm×300　mm　and　the　measurement　uncertainty　is　1.8　μm.　It　can　be　applied　to　measure　complex　geometries　without　nominal　mathematics　models.