The invention relates to an inertial energy storage and conversion device. According to the technical scheme, the device comprises a fixing frame, a power generator, a rotating shaft and a sliding block, wherein the power generator, the rotating shaft and the sliding block are mounted on the fixing frame; the device is characterized in that an input shaft of the power generator is coaxially arranged with the rotating shaft and connected with the rotating shaft through a planetary gear pair, and the planetary gear pair is composed of a sun wheel coaxially connected with the rotating shaft, an inner gear ring coaxially connected with the input shaft of the power generator and a planetary wheel rotatably mounted on a framework; the sliding block slides on the fixing frame in the axis direction of the rotating shaft, the rotating shaft is provided with a helical cam groove in the circumferential direction, the sliding block is provided with a cam push rod matched with the cam groove, and one end of the cam push rod is arranged in the cam groove. The inertial energy storage and conversion device is ingenious in structure, the power generator runs after an inertial sliding mode is converted into a rotation mode, the steering direction of the power generator remains unchanged, and the phase stability of the output current of the power generator is ensured.