The invention discloses a fixing device for mounting a faucet. The fixing device for mounting the faucet comprises a faucet body, a spherical valve, positioning holes and a sticky block; the right side of the faucet body is fixedly connected with a water outlet pipe; the lower end of the water outlet pipe is provided with a water outlet; the spherical valve is arranged and fixed at the upper end of the faucet body; the upper end of the spherical valve is connected with a handle; the left side of the faucet body is fixedly connected with a fixed plate; connecting holes are formed in the four inner corners of the fixed plate; connecting bolts are connected in the connecting holes; the positioning holes are formed in the inner sides of the connecting holes; and positioning bolts are connectedin the positioning holes. According to the fixing device for mounting the faucet, the fixed plate and the connecting bolts form a dismounting structure through the connecting holes, the connecting bolts can penetrate through the interiors of the connecting holes, the four corners of the fixed plate are tightly connected with a base body, multiple connections among fixed plates can be realized insuch a way so that the fixed plates are firmly and tightly connected, and then the fixed plates cannot be loosened due to overlong time.