A mine air quality composite index and ventilation energy-saving linkage system comprises a carbon monoxide detector, a hydrogen sulfide transmitter, a sulfur dioxide detector, a nitrogen dioxide transmitter, a dust detector, a programmable logic controller (PLC), a main fan, a main fan frequency converter, an industrial computer and a local area network, wherein the carbon monoxide detector, the hydrogen sulfide transmitter, the sulfur dioxide detector, the nitrogen dioxide transmitter and the dust detector are connected with the input end of the PLC, the output end of the PLC is connected with the main fan frequency converter, the main fan frequency converter is connected with the main fan, the PLC is bidirectionally connected with the industrial computer, and the industrial computer is connected with the local area network. according to the invention, a ventilation effect of the underground mining surface (or main working middle section) in a nonferrous mine is improved, and the underground working environment of workers is improved. A mine ventilation system time-interval seasonal frequency-conversion energy-saving control system is established to reduce the ventilation energy consumption of an underground ventilation system in the nonferrous metal mine by more than 14%.