A complex circuit board including a printed circuit board assembly (PCBA) and a flexible printed circuit (FPC) for providing driving signals for light sources is disclosed. The PCBA includes a supporting portion and a connecting portion. The light sources are disposed above the supporting portion. The connection portion contacts electrically with a contacting portion of the FPC. The contacting portion of the FPC has a fixing hole. The connecting portion of the PCBA has a fixing portion. Moreover, the FPC has two or more than two first bend portions on the contacting portion. The fixing portion of the PCBA is inserted into the fixing hole of the FPC to complete the complex circuit board without extra attachment units. Therefore, the assembly procedure is simplified to increase throughput and the cost is reduced.