Multiple-break arc-extinguishing lightning protection gap can effectively reduce the lightning tripping rate of 35 kV transmission lines, but there are few studies on lighting insulating coordination between insulator string and multiple-break arc-extinguishing lighting protection gap of 35 kV transmission line. Therefore, the lightning impulse characteristics and voltage-time characteristics of a 35 kV glass insulator string, a 35 kV composite insulator string and their multiple-break arc-extinguishing lighting protection gap with different clearance distances are experimentally studied. The experimental results show that multiple-break arc-extinguishing lightning protection gap can effectively protect insulator after lightning stroke; the insulation level of the multiple-break arc-extinguishing lightning protection gap is higher than that of the parallel gap devices at the same gap distance; the effective gap distance of multiple-break arc-extinguishing lightning protection gap is given by experiment. This conclusion can provide reference for the engineering of installing multiple-break arc-extinguishing lightning protection gap.