A composite insulating layer and a manufacturing method thereof. The composite insulating layer includes a socket substrate, a connection layer disposed on the socket substrate, a conductive metal layer disposed on the connection layer, an insulating metal layer disposed on the conductive metal layer, an insulating ceramic layer disposed on the insulating metal layer, and a electrodeposition layer disposed on the insulating ceramic layer. The composite insulating layer of the present invention can avoid the electromagnetic interference generated from the pins of the CPU and increase the stability of the CPU.