In order to solve the spindle rotation accuracy deterioration which was caused by the wrong and long timely balancing when applying mechanical motor drive balancing device, the influence coefficient method under noneline control online dynamic balancing is applied and the solution is discovered. The experiment platform was erected. Many trials were done by using the balance device in a manual way. Discoveries of the balancing weights moving strategies were made, and simulations were also tested by experiments. Given the final moving outcomes, the best moving path was selected. Results indicate that the balancing weights design is reasonable, which can adjust the weights timely and cut balancing time. The final outcomes meet the expectation. The spindle amplitude is decreased significantly and the balance efficiency also improved by applying the online dynamic balancing method. Such achievements can hold an important meaning and provide regulation strategies for the online dynamic balancing control technique.