Abstract: Abstract: In order to comply with increasingly strict emission regulations and energy-saving means, it is necessary to reduce emissions and improve fuel economy and a new generation of fuel injection system has to be developed. The introduction of high pressure common rail fuel injection system certainly plays an essential role in achieving the current performance of diesel engines. As the critical component of high pressure common rail fuel injection system, electronic controlled injector involves the multi-physical fields coupled together including mechanical field, electrical field and hydraulic field during the working process. The equations of the traditional fluid dynamics modeling method are complicated. Moreover, the accuracy of solution for the system state equations increases with the complex of the numerical solution method. Power bond graph is a system dynamic graphical modeling method. It can systematically describe the composition, the transformation of the power flow and the logical relationship between variables in the system. In addition, the basic physical characteristics of the system and the relations of energy conversion and conservation also can be represented using the power bond graph method. In order to predict the fuel injection quantity characteristics of the high pressure common rail fuel injection system under different working conditions, and reveal the multi-physical fields coupling characteristic mechanism of the system, a bond graph numerical model of common rail injector is proposed based on the composition and the operating principle of the injector in this paper. The fuel physical properties and variable liquid capacitance which have influence on the dynamic injection characteristics of the system have been taken into consideration. The common rail injector bond graph model includes the main components such as high pressure fuel pipeline, high pressure fuel pipeline joint, pipeline between inlet of the injector and nozzle volume, nozzle volume, pipeline between nozzle volume and needle chamber, nozzle, needle moving parts, control chamber and solenoid valve. The state equations are derived based on the bond graph model of the common rail injector, and the equations are numerically solved by Matlab programming. Fuel injection quantity of the system at different common rail pressure and different control pulse width is obtained. The test bench of high pressure common rail fuel injection system is established in order to validate the accuracy of the developed bond graph numerical model. The experimental measured fuel injection quantities of the system and the calculation values of the bond graph numerical model are compared at common rail pressure of 80, 100 and 120 MPa and control pulse width of 800, 1 000, 1 200, 1 400 and 1 600 μs respectively. It can be concluded that the developed bond graph numerical model of common rail injector for high pressure common rail fuel injection system has an acceptable calculation precision. The numerical model of common rail injector based on the power bond graph method can be used to predict the fuel injection quantity characteristics of the fuel injection system, and the bond graph method is an effective modeling tool for system dynamic numerical calculation. The results have a significant theoretical guidance for the multi-physical fields modeling of high pressure common rail fuel injection system and the numerical calculation of fuel injection characteristics of the system.