The invention discloses a VFTO (very fast transient overvoltage) measurement method and system, relating to the technical field of overvoltage protection of a power system. The high-frequency component of VFTO is measured by high-resolution continuous sampling, the power-frequency component in the low-frequency component of VFTO is measured by low-resolution single sampling, and the measured data of the high-frequency component and low-frequency component of VFTO is synthesized into a VFTO full waveform. Through the VFTO measurement method and system disclosed by the invention, the high-frequency component and low-frequency component of VFTO are separately measured, and the measured results are synthesized into a full-waveform VFTO, thus the difficulty of VFTO measurement and the requirement for the storage capacity for storing the measured results are reduced, and the accuracy of VFTO measurement is improved.