The invention relates to a special tool for a 500kV electric transmission line spacing bar and an application method thereof. The special tool comprises a cam wrench, a pull rod and an unthreaded pin, wherein one end of the pull rod is hinged to the cam wrench through a pin, the cam wrench is provided with a plurality of hole sites which can all be matched with the pin, the other end of the pull rod is connected with one end of the unthreaded pin through a chain, and the pull rod is provided with a row of inserting holes which can all be matched with the unthreaded pin in the length direction. The special tool has the advantages of universality, high efficiency, easy-to-master performance and the like, the hole sites are designed, the adjustable cam wrench and the pull rod can meet the assembling and disassembling needs of spacing bars of different models and different sizes, only one tool can replace various special tools originally, the tool can be carried portably and conveniently by installation personnel, the principle of lever and crowbar is mainly used, operation technologies and operation steps for assembling and disassembling the spacing bars are simplified, the working efficiency is greatly improved, the easy-to-master performance is achieved, the principle is simple, and training and using are easy.