The invention discloses a variable working condition active-control light-coal complementation indirect air-cooling generation system and method. The system comprises a boiler, a turbine, a generator, a high-pressure fed water heater, a low-pressure fed water heater, a deaerator, a steam extraction branch control valve, an absorption type refrigerator, an air-cooling condenser, a fed water branch control valve, a mirror field heat exchanger and a composite paraboloid light condenser. In the daytime in summer, the environmental temperature rises, the back pressure of the turbine rises, the turbine carries out low-pressure steam extraction to drive the absorption type refrigerator to cool air at the inlet of the air-cooling condenser, the back pressure of the turbine is made to reach the design valve, and the light condenser is used for replacing original low-pressure steam extraction to heat fed water. In the daytime in winter, the environmental temperature decreases, the back pressure of the turbine can keep the design value, the turbine carries out low-pressure steam extraction to continue expansion working, and the light condenser is used for replacing original low-pressure steam extraction to heat fed water. By means of the variable working condition active-control light-coal complementation indirect air-cooling generation system and method, the problem of the variable working condition operation efficiency of a traditional air-cooling unit is reduced in summer is solved, the annual average generation efficiency of the unit is improved, and efficient utilization of low-temperature solar energy is achieved.