The invention discloses an optimum dual-inlet and dual-outlet steel ball coal grinding machine direct-blow type powder-preparation control method. The method obtains the material position of the coal grinding machine after carrying out soft-measurement processing by collecting the noise material position of the coal grinding machine, the material position of pressure difference, the current of the coal grinding machine, one-time air quantity, one-time opening of the hot wind door and the cold wind door of an inlet, inlet temperature and outlet temperature; the control comprises material position control, air quantity capacity control, bypass air quantity control and the temperature control of the inlet and the outlet; the material position is optimized and the best material position of the coal grinding machine is searched online so as to ensure the combustion safety of the boiler and coal powder supply quantity when the load of the boiler is adjusted. The boiler combustion is optimized: according to the boiler technology, the load and the running working conditions, the powder supply quantity and the ventilation quantity of each coal grinding machine are optimized and the combustion efficiency of the boiler is improved. Malfunction diagnosis, running evaluation and analysis are carried out to the system and reasonable suggestions are provided so as to ensure the system to run continuously, stably, safely and economically; the optimum dual-inlet and dual-outlet steel ball coal grinding machine direct-blow type powder-preparation control method is widely applied to the dual-inlet and dual-outlet steel ball coal grinding machine direct-blow type powder-preparation system or industrial similar systems in other industries.