Abstract:An experiment was designed, the optical spot passing fiber was collected using CCD, the density distribution of the optical spot was analyzed, and the three-dimensional picture directly presented density distribution of the optical spot using self-written Matlab program. The issue that different sizes, different numerical aperture, before and after bending fiber led to optical spot uniformity was discussed, and some theoretical analysis was carried out. The results indicate that, the longer the fiber, the more uniformity the optical spot; the more similar the diameter of the fiber and the optical spot, the more uniformity the optical spot; after the fiber was bended, the optical spot becomes more obscure, more uniformity and weaker.