The invention provides a preparation method of spherical gallium particles with controllable size, which belongs to the technical field of the preparation method of gallium particles. The preparationmethod comprises the steps of (1) putting a polycarbonate porous membrane on the surface of liquid gallium without an oxide layer in a vacuum environment, and insulating for 5 to 7 hours at 30 DEG C to 50 DEG C; (2) after insulation, removing residual gallium from the polycarbonate porous membrane, dissolving the polycarbonate porous membrane in dichloromethane, and then respectively washing for 3to 5 times with ethyl alcohol and water; and (3) heating a solution obtained in the step (2) to 45 DEG C to 55 DEG C, and adjusting a PH value to 4.5 to 5.5, so that a gallium micron ball is obtained. According to the preparation method, the particle size of samples is uniform, and compared with a traditional template method, the particle size is reduced by 10 times. The prepared gallium micron ball has the characteristics of high conductivity, high surface energy, low melting point, low viscosity, low toxicity and the like, and therefore, the gallium micron ball can be used in multiple fields such as 3D printing raw materials, micrometer electrodes, drug carriers and the like. The preparation method has obvious advantages of simple synthetic steps, uniform shape of obtained particles andcontrollable particle size.