The invention relates to a traceless spliced cable protective jacket and a preparation method thereof, which belong to the technical field of electric power facilities, and solves the problem of providing a cable protective jacket which is high in strength, good in toughness, good in flame retardance, corrosion resistance and long in service life and a preparation method of the cable protective jacket. The protective jacket consists of sections A and sections B which are alternately arranged, the length ratio of the section A to section B is (2 to 4): 1, the section A and the section B which are adjacent to each other are connected in a fusion manner, and the outer surfaces of the section A and the section B are coated with protective paint C. The protective jacket is good in flame retardance, good in toughness, high in strength, resistant to sunlight, excellent in anticorrosion performance, and capable of effectively preventing the corrosion of acid and alkali salts; moreover, the protective jacket has good high temperature resistance, can effectively protect the cable for a long time and can prevent the safety potential danger; by virtue of the detection in test, the tensile strength of the protective jacket is greater than 35MPa, the elongation at break is 850 percent or above, the flame-retardant grade can reach grade A, and after being stored at the high temperature or soaked for a long time in acid and alkali salts, the surface of the protective jacket has no change.