For live line measuring zero-sequence parameters of triple-circuit coupled transmission lines of different voltage levels, the structure of transmission line is analyzed, A new live line measurement algorithm of zero-sequence parameters is developed combining the incremental method with "double-Π-shaped" circuit model and the least square method to work out the parameters. A simulation experiment of triple-circuit coupled transmission line of three different voltage levels is carried on in this paper. The simulation result with a maximum error of 5% proves the verification of the zero-sequence parameter measurement algorithm and can be applied to the zero-sequence parameters measurement of power system for triple-circuit coupled transmission lines.