Planetary gear transmission has properties of compact size, light weight, high efficiency, larger speed ratio, which lead this transmission type used more and more in industries. Transmission system with some planetary gear sets gives one or more degrees of freedom. Especially, planetary gear sets combined with brakes will give systems with different number of degrees of freedom as well as different kinematics diagrams. It is necessary to have a general method to represent the structure diagram to carry out the study of the kinematics of planetary gear systems. This paper presents an extended method to express the structure diagram and notation of planetary gear systems combined with brakes helping to research, calculate and design conveniently the planetary transmission systems for gearboxes.