The invention discloses a method for measuring inner diameter vertical difference of a high precision bearing. The method comprises the following steps: A. a base circle N is aligned, a ferrule is aligned and positioned by utilizing magnetism of an underpan of a roundness measuring equipment, and linear eccentricity e of the circle N is assessed by utilizing eccentric center assessment function of the roundness measuring equipment; B. the circle N is used as a basic circle, and a gauge head of the roundness measuring equipment is horizontally moved to an upper circle plane M to assess linear eccentricity e1 of the circle M; and C. the inner diameter vertical difference is calculated by utilizing a formula (see the formula in the right). The measuring method especially achieves good effects on measuring vertical difference (the ratio of inner diameter to height is 10 to 1) of inner diameters of double semi inner rings of a three or four point contact ball bearing with high precision inner diameter vertical difference of less than 1mu m, and fills in the gap in the industry.