By equipping NC machine tool with aprobe and corresponding measurement code,an onmachine measurement (OMM) system is formed.Using this technology,machining and inspection are integrated on a same equipment,so multiple clamping and repositioning errors can be avoided.The problems such as difficult modifying of rejected parts and long auxiliary time can be solved.Current research state and development of OMM were introduced,including OMM system development and application,compensation technology of probe pretravel error and OMM system development with correction function.Finally,some key problems in the field which needed to be solved and improved in the future were stated.