The invention provides a high-speed magnetically suspended flywheel energy storage device, which is characterized in that a casing is vertically mounted on a base, and the top of the casing is provided with a top end cover; a stator is vertically mounted at the lower part of the top end cover; a rotor coats outside the stator; the rotor is vertically integrated with a motor rotor; a passive magnetic suspension bearing is arranged between the top of the rotor and the stator for radial support; two interacting parts of magnetic poles of the passive magnetic suspension bearing are respectively arranged on the stator and the rotor, and the part on the rotor is a composite magnetic material containing permanent magnetic powder; and the bottom of the rotor is provided with a pin-type ball bearing, the top of the pin-type ball bearing is fixedly connected with an umbrella-shaped collet of the rotor, the bottom of the pin-type ball bearing is a sphere, the sphere is located in a bearing bush,the bearing bush is internally provided with lubricating oil, and the pin-type ball bearing forms axial support for the rotor. The structure 1) reduces the design difficulty of the bearing, 2) solvesproblems of the friction loss of the bearing and complex control of an active magnetic suspension bearing system, and 3) reduces the high-frequency harmonic eddy current loss of the rotor, reduces theheat generation amount of the rotor and improves the number of full-power rated capacity operation times of the flywheel in unit time.