In the disclosure a fluid mixing valve for mixing a first fluid and a second fluid is provided, comprising: a housing; a balance valve module for balancing pressure between the first fluid and the second fluid, comprising a first fluid inlet, a second fluid inlet, a first fluid outlet in fluid communication with the first fluid inlet, and a second fluid outlet in fluid communication with the second fluid inlet; an adjustable valve module disposed on the balance valve module, comprising an inner casing member, flow-rate adjustment seat secured to the inner casing member, and a temperature adjustment shaft received in the inner casing member; and a mixed fluid discharging passage.