The invention provides an overvoltage measuring sensor for an overhead transmission line based on a coupling electric field, and relates to an overvoltage online monitoring sensor of the overhead transmission line. The overvoltage measuring sensor provided by the invention mainly comprises a sensor shell, an insulating pad, a fixing board, a partial voltage capacitor group, a matching resistor, a coaxial cable, an inner screening shell, a data collecting unit and the like. The overvoltage measuring sensor provided by the invention has the advantages of simple structure, convenience in mounting and dismounting, low cost, high accuracy of overvoltage measurement, good linearity, high accuracy, strong generality, wide application range, safe and reliable use and the like. With the adoption of the overvoltage measuring sensor provided by the invention, overvoltage online monitoring can be conveniently carried out on the overhead transmission line. The overvoltage measuring sensor provided by the invention can be widely applied to the overvoltage online monitoring of the overhead transmission line, and is particularly suitable for monitoring overvoltage of 110-1000 kV high-voltage overhead transmission lines on line.