The MyM package is used to define, visualize and run mathematical models of dynamic systems. Without the help of a programmer, users just have to write down the mathematical equations and they can build a graphical user interface themselves by just drawing graphs and charts on a canvas. This article introduces the MyM Language and the MyM tools. An example is given to describe how to construct and dynamically visualize the mathematical model. Finally, it shows the architecture and functional characteristics of the MyM. The application of the software is discussed.