The distance-measuring accuracy of conventional distance protection based on one-end sampling data from single line is difficult to satisfy specification requirement for parallel lines on same poles（PLSP）affected by zero-sequence mutual inductance between the lines.Using one-end sampling data from single line，a new algorithm for distance protection of single-phase grounding fault of parallel transmission lines，which can consider the effect of zero-sequence mutual inductance of adjacent lines is proposed.It achieves accurate distance-measuring.Through analyzing fault model of single-phase grounding fault of PLSP，the fault distance accurate expression with zero-sequence currents of parallel lines is derived.Further，the expression between zero-sequence current of the adjacent parallel line is analyzed.By substituting the estimate value of fault location，zero-sequence current of neighbor line can be represented by zero-sequence currents of the protection site so as to calculate zero-sequence current of PLSP with one-end sampling data from single line.Finally，an accurate fault impedance can be calculated by one-end sampling data from single line with consideration of the impact of mutual coupling effect.Simulation results with PSCAD show that the algorithm is insensitive to the accuracy of estimated fault location and has good adaptation capability for system operation.It can increase impedance-measuring accuracy of single phase grounding fault for PLSP.