A method and a device for nano machining a water-dispersed pearl are provided. A water-dispersed pearl powder material while stored in a material bucket is fed into a milling machine by a material feeder. In a material-feeding milling room of the milling machine, a rotary member is rotated to drive a powder-crushing roller to crush and grind the water-dispersed pearl powder in a circular material groove. An upward effluent pipe connected to a discharge hole located on an upper part of the milling room is configured with an exhaust fan, and a gas permeable powder-collecting bag communicated with a connecting curved pipe is served as an exhaust end of the exhaust fan. By utilizing the operation of the exhaust fan drawing wind from the milling room and the function of ultra-fine nano pearl powder particles entrained by air to be drawn into the gas permeable powder-collecting bag, resulting in air in the gas permeable powder-collecting bag to be expelled to the exterior naturally, the nano pearl powder particles can be continuously and collectively accumulated in the gas permeable powder-collecting bag to acquire a nano pearl powder product. Therefore, the water-dispersed pearl power can be easily processed into nano pearl power, and also efficacies of high nano machining efficiency and stable quality of pearl power can be obtained.
