The invention relates to the technology of ultra-high voltage direct-current transmission, and in particular to a distance measurement method for a ground electrode line fault of an ultra-high voltagedirect-current transmission system. The method comprises the following steps of deriving a solution formula of a transition resistance based on an impedance analysis method, and determining the transition resistance of a fault point after a fault occurs; establishing a function relation expression between fault positions and transient over-voltages under different transient resistances by use ofa regression analysis method; and obtaining the transient overvoltage at a measurement terminal and calculating the transient resistance when the fault occurs, and substituting the transient overvoltage and the transient resistance into the function relation expression to obtain the fault distance. According to the method, after the function relation expression between the fault positions and thetransient over-voltages under different transient resistances is established by use of the regression analysis method, the fault distance can be quickly calculated through simple calculation and is high in precision, the clearance efficiency of the ground electrode line fault is improved, and the method has important practical value for improving the operation stability of the ground electrode system.