Aiming at fouraxislingkage CNC process technology for hourglass worm, some new requirements to structure of machining unit have been put forward. Based on research and experiment to a fouraxislingkage CNC grinding machine of hourglass worm, the key geometrical size and moving parameters were introduced.The effects of the arm length of the grinding head rotary table to the programs trajectory and interpolation rotary angle were analyzed also.At same time,the effects of the arm length, machining center distance and transmission ratio to move parameters on both X axis and Z axis were given in detail.The experimental data verified in workshop practice are useful certainly.