Waterproof optical fiber

The invention relates to a waterproof optical fiber. The waterproof optical fiber comprises a fiber core and a coating, and the coating peripherally surrounds the fiber core which is formed by doping of two fiber cores with different refractive indexes. The coating comprises a primary coating layer, a secondary coating layer and a waterproof layer sequentially from inside to outside, the primary coating layer and the secondary coating layer are made from ultraviolet-cured resin which comprises urethane acrylate and a light initiator, and a polyisocyanate component in the urethane acrylate is aromatic polyisocyanate. A plurality of holes extending along a center axis of the optical fiber are formed between the primary coating layer and the secondary coating layer, and a residual stress in an internal region inside a circumscribed circle of the holes is a compression stress. The waterproof layer is made from liquid nylon and 20-40 micrometers in thickness, and the liquid nylon is 1.11kg/L in density, 1.50-1.52