The invention relates to the technical field of online monitoring of alternating current voltage and voltage measurement of zero-value insulators, in particular to an alternating current high voltage sensor with a novel film sheet structure and a measurement method. The sensor comprises a high voltage electrode, an FP sensor electrode, an FP sensing unit, a fine tuning device, a base, a fiber and a glass sleeve. The high voltage electrode and the FP sensor electrode are up-down coaxially arranged, and a certain distance is kept therebetween. An axis center stair hole is arranged in the FP sensor electrode. The fine tuning device is installed on the lower part of the axis center stair hole. The FP sensing unit is adhered to the center of the end face of the fine tuning device. The fiber successively passes through the center of the base and the center of the fine tuning device, and enters the FP sensor. According to the invention, by providing the fiber Fabry-Perot high voltage alternating current voltage measurement method adopting a snake-shaped structure processed by use of the MEMS technology, a new detection technology is provided for online monitoring of the high voltage and voltage measurement of the zero-value insulators and the sensitivity in high voltage alternating current voltage measurement is quite high.