The invention discloses an indoor air purification system for heating fresh air through solar energy. The indoor air purification system is characterized by mainly comprising a flat plate heat collector, a heat collector cold water pipe, a heat collector hot water pipe, a water tank water outlet pipe, a water compensation pipe, an electrical heating device, a heat preservation water tank, a shower nozzle, a water tank water inlet pipe, a coil upper portion water pipe, a coil lower portion water pipe, a heat collector water pump, a coil water pump, a tee joint reversing valve, an electromagnetic valve, a coil, a condensate water tray and a condensate water pipe and further comprising an air circulating and purifying system. According to the indoor air purification system, outdoor fresh air is heated through solar energy, influence on indoor heat load is reduced, meanwhile indoor positive pressure is guaranteed, air volume required to be discharged out seeps out of window seams or door seams, and external interference is further reduced; when outdoor fresh air is not needed, an indoor circulating mode can be started, indoor air is purified, and indoor formaldehyde, PM2.5 and other harmful substances are removed; hot water in the heat preservation water tank can be fully utilized in transition seasons, and solar energy utilization is more efficient.