The invention discloses a real-time dynamic motor system energy saving amount accounting method, which comprises the steps of regressing a load rate-efficiency curve of a dynamic motor system by using real-time test data of each device of the dynamic motor system, solving to acquire the technology energy saving amount and the management energy saving amount before and after transformation by using a relation between the efficiency and the energy consumption. The invention further discloses a dynamic motor system real-time monitoring system applying the accounting method, which comprises a device layer, an intelligent instrument layer, a control layer, a data transmission layer, an intelligent gateway and an information and monitoring platform. The method disclosed by the invention can carry out precise accounting on the management energy saving amount and the technology energy saving amount in the dynamic motor system, perform forecast and estimation on the energy saving potential and form an energy saving and emission reduction control strategy, and can carry out dynamic and real-time adjustment on an enterprise motor system by being combined with the dynamic motor system real-time monitoring system so as to realize the optimal energy consumption of the system.