The invention relates to a tool fixture for a CNC engraving machine and a use method and belongs to the field of processing of watch parts. A watchcase of a watch usually needs to be fixed in the processing process, a current tool fixture cannot fix the watchcase firmly, and the watchcase is rotated frequently. The tool fixture comprises a base, an extension nozzle, a pull core, a pull core nut, ahandle, a positioning pillar and a positioning needle. The extension nozzle and the positioning pillar are both installed on the base, the pull core is installed on the extension nozzle, and one endof the pull core penetrates through the extension nozzle. The pull core nut is installed at one end of the pull core, the pull core nut props against the extension nozzle, the handle is installed on the pull core nut, and the positioning needle is installed on the positioning pillar. The watchcase to be processed is arranged outside an expansion ring in a sleeved manner, falling of the watchcase to be processed can be prevented through a supporting boss, the pull core is pulled downwards through the pull core nut, the watchcase to be processed is expanded and tightened through the expansion ring, and the watchcase to be processed is fixed preliminarily.