As hazardous molecules such as HC, CO and Nox from automobile exhaust and air pollution can cause allergy and coughing and trigger cancer, Green Island Smart Ecological Purification System has thus been designed. By heating up ceramic substrates, the Green Island system transforms hazardous molecules into nutrients and oxygen required for algae cultivation, and electricity generated by algal photosynthesis is used for reproduction and cultivation lights to keep the temperature of ceramic substrates in the Green Island system to boost circulation. Additionally, aquatic plants growing on Green Island can exchange nutrients with algae to form ecological symbiosis. Excessive algae which can be picked and made into biomass petroleum become energy suppliers. Green Island not only purifies air, but also creates circular ecology prospering with cities.