An innovative multi-layer coating method has been studied for preparation of gradient refractive index (GRIN) lenses. The preparation method employs a polymer optical fiber as a core fiber, which is subjected to a repeated process of alternating peripheral coating with polymer solutions of different refractive indices (RIs). Three polymer Solutions with different R-Is were used as coating solutions. The coating behavior of the polymer solutions on the periphery of the core fiber was studied by Use Of Continuous multi-coating equipment. Regression analysis showed that the dimensionless coating thickness was well correlated with the capillary number, Ca, being proportionally dependent on Ca to the two-third power. The coating thickness was also dependent on the depth of the polymer solution in the reservoir.