The invention discloses a direct current power distribution network line single-pole ground fault locating method. The method comprises the steps that 1, a fault current differential initial value expression is obtained according to a transient characteristic equation of a fault current; 2, a fault current differential initial value is replaced through an interpolation algorithm; 3, a fault location value expression containing the fault current differential initial value is obtained; 4, the fault location value expression is combined with a loop current equation, and a fault-based location equation is obtained; 5, voltage and current value information before and after a single-pole ground fault happens is obtained, the fault current differential initial value obtained in the step 2 and the fault location equation obtained in the step 4 are combined, and a fault location value is obtained. According to the direct current power distribution network line single-pole ground fault locating method, calculation is easy, the application range is wide, the method is free of influence of factors such as transition resistance, the calculation result can be used for offline maintenance, automatic operation can be achieved, high resistance to transition resistance is achieved, and when the transition resistance is increased, the high location precision is still achieved.