The invention discloses an automatic target replacing device. The automatic target replacing device is applied to an electron beam evaporation deposition device. A use method of the automatic target replacing device comprises the following steps that (1) a target material is fed in real time, wherein when the evaporation deposition technology is conducted, according to data of a second sensor, a control unit of a feeding mechanism automatically controls a second servo motor in real time to drive a feeding platform to upwards feed target materials in a target container in real time according to the consumption of the evaporation deposition technology; (2) the target material is automatically replaced, wherein a third servo motor drives a target material disk to rotate, a second target material cavity, provided with the target material, on the target material disk is rotated to the position under the target container to accurately coincided with a cylindrical cavity of the target container, the feeding platform moves upwards to be under the target material of the second target material cavity and supports the target material, then a clamping door is opened, the feeding platform continues moving upwards to feed the target material into the target container and is tightly combined with the target material in the target container, and then the feeding mechanism is stopped; and (3) a replacement target material is pushed into the target material disk.