A control valve of a manual/automatic and cold/hot water faucet includes a sliding member, a linking member, and an operating member. The sliding member has a notch. The linking member is recessed with a connecting groove. The operating member has a valve stem and a linking portion. The linking portion drives the linking portion and the sliding portion through the connecting groove. The valve stem, the connecting groove and the central axis are arranged concentrically, so that the overlapping area of the notch and the cold water hole is equal to the overlapping area of the notch and the hot water hole to keep the same ratio of cold water to hot water in an automatic mode to dispense water, thereby increasing the safety in use.