The shortcomings of traditional gear pump and the development of gear pumps were introduced. Three different meshing types of balanced planetary transmission gear pumps were put forward.Balanced external meshing gear pump, balanced compound gear pump and balanced internal meshing multi-gear pump. The working principles of them were expatiated. The flow characteristics and mechanical properties of balanced planetary transmission gear pumps with three different meshing types were analyzed. It was pointed out that the problem of unbalanced hydraulic radial force was overcome by the balanced planetary transmission gear pump from the structure, at the same time of greatly increasing displacement of the gear pump，its flow pulsation was reduced. The balanced planetary transmission gear pump is the development direction of gear pump in the future.