An automatic power and efficiency analysis tool was developed by utilizing Mathematica programing software. The tool consists of four modules and use the algorithm based on constraint method. This package is capable of analyzing arbitrary epicyclic spur gear transmissions with one or two-dof. The Graphic User Interface (GUI) can display the constraint matrix, normal internal and external powers, virtual internal and external powers, efficiency expression and efficiency profile. In addition, normal power flow and virtual power flow diagrams are integrated in the GUI for power flow pattern observation.