A new closed loop flow controlling principle through correcting the valve’s opening area while load pressure is changing is carried out. Further more a principle using only one proportional valve to compound control pressure and flow is suggested. By using very simple proportional throttle valve in structure, the functions that five kinds of proportional valves or any two of them combined possess can be complimented. After analyzing, comparing, and testing the dynamic and static characteristics of valve with different controlling principles and main valve structure styles, the optimized structure styles and control methods are achieved. A new closed loop flow controlling principle through correcting the valve’s opening area while load pressure is changing is carried out. the analyzes that compare the dynamic and static characteristics of valves with different controlling principles and main valve structure styles, the optimized structure styles and control methods are achieved.