Abstract: A frame structure for ceiling lighting device is provided, which includes a plurality of first frame bars, a plurality of second frame bars and a plurality of corner braces. Each first frame bar includes a first frame bar body and a first chamber structure disposed on one side of the first frame bar body. Each second frame bar includes a second frame bar body and a second chamber structure disposed on one side of the second frame bar body. Each corner brace includes a first extension arm inserted into an opening at one end of the first chamber structure of one of the first frame bars and a second extension arm inserted into the opening at one end of the second chamber structure of one of the second frame bars, such that the first frame bars and the second frame bars can be combined with each other.