The invention discloses a running brake boosting system of an electric automobile, which comprises a brake pedal switch, a vacuum pressure sensor, a whole vehicle controller, an atmospheric pressure sensor, an electric vacuum pump, a relay group and a storage battery group, wherein the whole vehicle controller is respectively connected with the brake pedal switch, the atmospheric pressure sensor,the vacuum pressure sensor and the electric vacuum pump in a control mode; the storage battery group is electrically connected with the electric vacuum pump through the relay group; the relay group comprises a common relay and a standby relay which are in parallel connection; and the two relays are respectively connected with the whole vehicle controller in the control mode. The invention furtherdiscloses a control strategy and fault diagnosis method of the running brake boosting system of the electric automobile. By the adoption of the running brake boosting system of the electric automobileand the control strategy and fault diagnosis method thereof, the control strategy of the electric vacuum pump meeting driving braking assistance of the whole vehicle is formulated by collecting dataof atmospheric pressure, system vacuum pressure, brake switch and the like, a driving control requirement of the electric automobile is better met, and a set of more effective driving fault warning strategy is formed.