The invention belonging to the technical field of on-line monitoring of a lightning arrester especially relates to a wireless-synchronization-technology-based integrated on-line lightning arrester resistive current monitoring apparatus that is used for gapless metal-oxide lightning arrester. The wireless-synchronization-technology-based integrated on-line lightning arrester resistive current monitoring apparatus comprises a housing, a resistor piece, and an electronic timekeeper and mechanical timekeeper unit. The resistor piece and the electronic timekeeper and mechanical timekeeper unit are installed in the housing; and a front window is arranged on the housing. The electronic timekeeper and mechanical timekeeper unit consists of an electronic timekeeper and a mechanical timekeeper that are connected in series. The series-connection electronic timekeeper and mechanical timekeeper are connected in parallel with the resistor piece. The mechanical timekeeper is displayed from the front window. And an aviation plug is arranged at the lower cover of the housing. The monitoring apparatus has advantages of simple structure, reasonable design, and advanced structure. On-line monitoring of resistive currents of lightning arresters with all voltage levels is realized; the resistive currents of lightning arresters are measured precisely; and thus the operation information of the lightning arresters is obtained accurately.