The invention discloses a flywheel energy storage device slowing down based on a friction wheel. The device comprises a brushless permanent magnet motor and a vacuum cavity, wherein the vacuum cavitycomprises a first-stage vacuum cavity and a second-stage vacuum cavity installed from the bottom up, a first-stage installation hole is formed in the bottom of the first-stage vacuum cavity, a flywheel is arranged in the first-stage vacuum cavity, a first-stage support mechanism is installed in the first-stage installation hole, the first-stage support mechanism is installed and connected with thelower part of the flywheel, a flywheel output shaft is arranged in the flywheel, a planet wheel reduction mechanism is installed and arranged in the second-stage vacuum cavity, the flywheel output shaft stretches into the second-stage vacuum cavity to be connected with the planet wheel reduction mechanism, the brushless permanent magnet motor is installed in the second-stage vacuum cavity, an electromagnetic pin is arranged on the brushless permanent magnet motor, and the electromagnetic pin output shaft of the electromagnetic pin stretches into the brushless permanent magnet motor to be connected with the output end of the planet wheel reduction mechanism. The flywheel energy storage device slowing down based on the friction wheel provided by the invention has the characteristics of lowself-discharge rate, small stand-by loss and good heat dissipation performance.