Abstract: An assembling device for bed assembly, including a main stand, a bracket and a rest assembly. The bracket is fixedly disposed on the main stand and extends from the main stand. At least one support member is disposed on the bracket and upward extends therefrom. The rest assembly is mounted on the bracket and has at least one locating board for conveniently resting one or more bed frames thereon and quickly assembling the bed frames at lower ratio of defective products. After assembled, the bed assembly is conveniently carried away from the assembling device.