Abstract: With the continuous development of power grids, the transmission corridors are increasingly narrowing, and it is very common for the triple circuits to share a part of the corridor. Currently, there is no corresponding line distribution parameter measurement method. This paper establishes a triple-circuit non-full-line parallel line distributed parameter model. Considering the non-uniformity of line parameters, an accurate measurement of the zero sequence parameters of triple-circuit non-full-line parallel lines is proposed. This method uses the Laplace transform to completely obtain the transmission matrix of the lines. With the synchronous measurement technology, the voltages and currents at the heads and ends of the lines are measured synchronously under 4 independent measurement modes. These voltages and currents are substituted to the proposed method to solve the zero sequence distribution parameters accurately. The accuracy of the proposed method is verified by the PSCAD/EMTDC simulation software. Compared with the existing measurement methods, the proposed method has higher measurement accuracy than the existing methods.