The utility model discloses a standard capacitor provided with an embedded a reverse connecting unit and used for testing high voltage medium loss. The standard capacitor comprises an inflatable high voltage standard capacitor and a reverse wire connecting unit; the reverse wire connecting unit comprises a reverse connecting current sampling unit, an optical fiber for transmitting reverse connecting signals and a photoelectric signal output port; the reverse connecting current sampling unit is arranged in an anti-corona cover; the photoelectric signal output port is arranged on a standard capacitor base; and the optical fiber for transmitting reverse connecting signals penetrates through an insulating barrel, one end of the optical fiber for transmitting reverse connecting signals is connected with the reverse connecting current sampling unit, and the other end of the optical fiber for transmitting reverse connecting signals is connected with the photoelectric signal output port. With the adoption of the standard capacitor, the technical problem of field connection of the existing high voltage standard capacitor in a reverse wire connecting test is solved, potential safety hazard can be avoided; and the security and reliability of the field test are greatly improved.