The invention discloses a multi-grain-size uniform spherical powder batch preparation device and method based on uniform metal droplet spraying. The multi-grain-size uniform spherical powder batch preparation device and method based on uniform metal droplet spraying are used for solving the technical problem that an existing uniform spherical metal powder preparation method is low in productivity. According to the technical scheme, electric signals are input into piezoelectric ceramics to generate mechanical vibration of the piezoelectric ceramics, generated mechanical vibration enables molten metal at nozzles to generate a certain speed, and accordingly a certain amount of metal fluid is sprayed out, and fluid sprayed each time forms a metal droplet. By controlling the pressure of the molten metal in the device and vibration of the piezoelectric ceramics, the droplets uniform in size and consistent in thermal history can be obtained. The flying speed of the droplets prepared through the method is low, the droplets can completely solidify within a very short flying distance, and the droplets are small in vibration and high in degree of sphericity. The multiple piezoelectric ceramics are installed on the device in the longitudinal direction and the transverse direction, and meanwhile, the multi-spraying-hole nozzles of different sizes are used for preparing a large amount of multi-grain-size uniform spherical powder at a time.