The invention discloses a broadband transient voltage division measurement device and a method. The device comprises a high-voltage arm unit, a low-voltage arm unit and a broadband transient measurement unit, wherein the high-voltage arm unit is used for dividing high voltage of a to-be-measured line to obtain divided low voltage, and transmitting the divided low voltage to the low-voltage arm unit; the low-voltage arm unit is used for transmitting the divided low voltage to the broadband transient measurement unit; and the broadband transient measurement unit is used for measuring the dividedlow voltage transmitted by the low-voltage arm unit, and determining the high voltage of the to-be-measured line according to the divided low voltage and a voltage division ratio. The device adopts alow-inductance ceramic capacitor and a non-inductive resistor for multi-stage series connection, can be directly connected to a power transmission line in a hanging manner to measure high voltage ofa to-be-measured circuit in real time, is high in measurable voltage amplitude, broad in band and low in external environment influence, can determine an actual waveform of overvoltage, and has an important significance in safe and stable operation of the power transmission line.