Machine tool stiffness is a principal factor affecting machine tool precision, traditional methods can only be used to detect limited categories of machine tools. The paper introduces a new scheme to detect machine tool stiffness on the basis of dynamic detection of machine tool stiffness considering its characteristics and stress state during processing. An experiment conducted in turn-milling machining center CH7516GS indicated by comparison that statics analysis of finite elements matched the experimental result well, which provided precise original data for design of improved machine tool precision and access to design of precision detection equipment for other types of machine tools.