The utility model discloses an optical core protecting tube inside an optical cable splice casing, which comprises an external protecting tube. One end of the external protecting tube is bent relative to the other end thereof, an included angle thereof is alpha, a steel tube is arranged inside the external protecting tube, a conical converging cavity and a mounting hole are arranged inside the steel tube, the conical converging cavity is communicated with the mounting hole, an internal protecting tube is arranged inside the external protecting tube, one end of the internal protecting tube is located inside the mounting hole, and the smallest diameter of the conical converging cavity is smaller than or equal to the diameter of an inner cavity of the internal protecting tube. A made-to-measure optical chip protecting tube is additionally arranged on a portion easy to be damaged inside the optical cable casing through analyzing type selection of materials of the protecting tube and measuring size and appearance of the protecting tube according to the inner structure of the casing and characteristics of optical chips, and the external protecting tube matches with the internal protecting sleeve so as to prevent the optical chip from being worn by sharp blurs at the mouth of the steel tube and affected by field environments and simultaneously protect the optical core against shaking and being broken randomly.