The invention relates to a metal powder preparation device and method therefor. The device comprises an atomization furnace, a heater, a cooler, an atomization chamber, an atomizer, a pneumatic classifier, a middle bin, a sieving funnel, a screening machine, a deduster, a balance tank, a shell-and-tube heat exchanger, a vacuum obtaining device, a control system, an infusion tube, a conduit, a pipeline, a gas channel, a pneumatic butterfly valve, an electromagnetic valve and the like. The method comprises atmosphere preparation, metal smelting, infusion, centrifugal atomizing, pneumatic classification, mechanical screening, gas purification, cooling and the like, the metal is smelted and treated so as to be poured onto the atomizer for centrifugal atomization to form powder, the powder is classified by the pneumatic classifier, after classification, rough powder is screened by the mechanical screening so as to obtain the finished powder, fine powder is sent into the deduster by airflow for purification, the purified gas is driven by a high pressure centrifugal fan so as to be speeded up to be atomized and classified again after being subjected to heat exchange through the shell-and-tube heat exchanger. The device can be used for continuous production of spherical powder below -320 meshes, and the oxygen content is less than or equal to 80ppm.