a measuring system for flatness degree measurement includes a measuring instrument and a processing device . the measuring instrument has a base , a guide column , a sliding member , a digital micrometer and a holding member . the guide column is vertically attached to the base . the sliding member is moveably attached to the guide column . the digital micrometer is firmly fastened to the sliding member . the holding member is configured for fixing a workpiece and has a reference - standard surface formed thereon . the processing device electronically connects with the digital micrometer . the processing device receives a plurality of measured values from the digital micrometer and displays a testing result after processing the measured values .