A temperature adjustable water mixing valve having a cold water inlet, a cold water outlet, a hot water inlet, a mixing water outlet, and a valve core configured to open or close water channels. The temperature adjustable water mixing valve further includes a pressure relief channel between the cold water inlet and a port connected with a water storage device. The channel is equipped with a check valve allowing water to flow from the water storage device to the cold water inlet. The temperature adjustable water mixing valve opens the check valve to discharge toward the front-end water source when the inner pressure in the water storage device is high.