According to the needs of watercooling and spraying systems on mine excavation equipment, then problems and defects on existing water valve，such as spool and spring were easy to be corroded and jammed,and leaking hydraulic oil and water caused by seal failure were summarized. A new type of hydraulic control water medium on/off valve was developed based on hydraulic fluid dynamics, some designing methods of hydraulic valve，analyzing advantage and disadvantage of typical orifices and internal structure of existing hydraulic valve. This valve has some advantages such as simple structure,better antipollution,not easy to corrode of key parts, easy to maintain,and so on. It also can meet the requirement of coal mine equipment.