A method for preparing optical fibers formed with high-particle-coated porous polymeric outer coating layer is provided. The method includes preparing a coating suspension solution by dispersing a plurality of particles into an organic solvent system, immersing one or more optical fibers into the coating suspension solution, removing the one or more optical fibers from the coating suspension solution to form high-particle-coated porous polymeric outer coating layer after drying. Concentrations and compositions of the particles in the coating suspension solution, concentrations and compositions of the organic solvent system, the period of time of immersing, or the external environment are adjusted such that the optical fibers is formed with high-particle-coated polymeric outer coating layers having desirable coating masses, coating thicknesses, or coating morphologies.