This paper presents a useful method of registration in manufacturing of shadow color mask for cathode ray tubes of the FTM (Flat Tension Mask) type, wherein the shadow mask and front panel are interchangeable when mask-panels are assembled, which is called ICM system. Theoretical analysis and alignment process are presented. The pattern of mask aperture is registered with a screen pattern of corresponding geometry of the panel in flat tension mask tube. Registration accuracy of panel and mask affects the purity of color cathode ray tube concerned with mislanding. It tries to minimize the misregistration caused by variances, which are mechanical error, mask stretching position error, restrictive number of fiducial point, etc.