The invention discloses a testing method, testing device, a testing equipment and a testing system of a very fast transient overvoltage (VFTO) sensor, wherein the testing device comprises a signal generating module, a signal collecting module and a controlling processing module. The signal generating module is connected with a high voltage electrode and used for generating input signals of the high voltage electrode; the signal collecting module is connected with the VFTO sensor and used for collecting output signals generated by the VFTO sensor according to the input signals; and the controlling processing module is connected with the signal collecting module and used for determining frequency characteristics of the VFTO sensor according to the output signals and the input signals. The application of the testing method, the testing device, the testing equipment and the testing system of the VFTO sensor can avoid the shortcomings existing in manual testing of the VFTO sensor and enable testing of the VFTO sensor to be more accurate.