Abstract: Some method in determining the location of “unbalance” and certain problems, such as accuracy, in the development of dynamic balancing have been discussed in this paper.The new method for determinating the location of “unbalance” is given by authors which fully comprehends the advantages of the method of waft meter and that of stroboscope commonly practiced in many balancing machines.Two principles ofr designing the fully-auto dynamic balancing machine have been discussed in detail; the one uses the xciting voltage of polarized relay for the purpose of control, and the other uses the property of single-stability circults. Both methods may be applied to find the loations of “unbalance” and to make corrections at different working positions.Besides, the paper briefly status the general trend of development of balancing machine.