Abstract: A fluid injection pressure control syringe is a convenient device to reflect changes of fluid pressure inside the syringe barrel or close communicating vessel by utilizing the change of compression amplitude of a spring with certain elasticity coefficient, including syringe barrel, pushrod with sealing gasket, spring, indication pole with little sealing gasket on the surface of indication pole, there is pressure scale or pressure range information, and hole cap. The main physical principle A, P=(F1+F2)/S; Physical principle B, F1=K(L0?L). P is the pressure of the fluid in the syringe barrel; F1 is the spring compression reaction force; F2 is the sliding friction force between sealing gasket and sub-barrel wall (negligible when micro); S is the cross-sectional area of the sub-barrel inner lumen. K is the elastic coefficient of the spring, L0 is the original length of the spring, and L is the length after compression.