Method, device, and automatic control system for determining air intake amount for opposed firing

A method for determining an air intake amount for opposed firing, comprising: determining an opposed firing operational oxygen amount, an excess air coefficient in a primary combustion zone, and a burn-out air amount allocation coefficient for a burn-out air box at each layer; and determining, according to a total fuel amount inputted from a furnace wall at which said burn-out air box is located and analytical data of properties of inputted coal in addition to the opposed firing operational oxygen amount, the excess air coefficient in the primary combustion zone, and the burn-out air amount allocation coefficient, an air intake amount for opposed firing. Also provided are a device and automatic control system for implementing the method for determining an air intake amount for opposed firing, wherein an air intake amount during a low-NO x opposed firing process is automatically controlled during furnace operation, thereby ensuring highly efficient combustion while maintaining a low level of NO x concentration at a furnace outlet.