A method of making soybean milk applicable to a device of making soybean milk is provided, wherein the device includes a base, a holder for carrying a capsule, a liquid supply mechanism and an injection head the capsule includes a container and a diaphragm for closing the container, and the method of making soybean milk includes: (a) making the injection head pass through the diaphragm to inject liquid into the capsule, wherein the liquid permeates a soybean powder layer to reach a planar, concave or convex splashing portion at a bottom of the capsule to form a liquid flow passage and (b) continuing injecting liquid, by the injection head, into the capsule, wherein the liquid is splashed by the splashing portion to gradually dissolve the soybean powder upwards from the bottom of the capsule until the soybean powder is completely dissolved.
