In order to improve the ball forming accuracy and grinding efficiency of precision ball, the design structure of V-shaped groove with variable diameter and partial groove was proposed for precision ball grinding disc. By establishing the geometric motion model of the single ball, the geometric motion of the precision ball was analyzed, and the relationship between the self rotation angle of the ball and the groove deflection angle and the groove radius of the grinding disk was obtained. Taking V-shaped groove with 90° groove angle as an example, the influence of partial ditch V-shaped groove structure on the equal probability of grinding under the condition of variable radius was studied. Combined with the actual production condition, the reasonable value of the deflection angle of the V-shaped groove with partial groove was proposed. By using numerical simulation technology, the spherical machining track and track distribution density were simulated and analyzed. The results show that by using the V-shaped groove with the partial groove, the distribution of grinding trajectories can be more uniform and the cutting equal probability of the ball can be improved. The structure is conducive to improving the grinding quality and machining efficiency of the grinding ball.