Abstract: Aiming at the problem of self-balancing control of a cubical robot, this paper researched the dynamic modeling of the cubical robot balancing on its edge. Using the prototype of cubical robot built as the subject, the dynamic model was derived with Lagrange method and Kane method. The correctness of the model was verified in theory by comparison of the two methods and numerical simulation. The controller designed based on the mathematical model was used in balance control of the physical cubical robot prototype. The correctness of the model was verified again with the expected effect. This dynamic model can provide a base for further study of balance control of a cubical robot balancing on its corner.