The bond graph method is used to analyse and model dynamics of hybrid electric system based on Ravigneaux Planetary Mechanism. Bond graph models are built in different structural form, general equations of torque and speed are derived, and operating modes achieved in different structural form are in consideration. At the same time, requirements of control system in different operating modes are illustrated and analysed, which help lay the foundations for modeling and simulation of HEV system based on Ravigneaux Planetary Mechanism.