NOVELTY - Harvesting Chlorella comprises (i) adding surfactant into Chlorella raw material liquid, and adjusting the pH value; (ii) adding the obtained mixture into bubble column of foam separation device; and (iii) opening the compressed nitrogen tank valve, opening the valve connected to the gas meter, adjusting the separated gas velocity, until the bubble column lower liquid color does not change; then closing the compressed nitrogen tank valve until there is no bubble flow into the bubble column, and measuring the amount of liquid collected in collection bottle and bubble column.    USE - The method is useful for harvesting Chlorella (claimed).    ADVANTAGE - The method is economical, has high efficiency, good environmental protection, and enrichment and high recovery ratio.    DETAILED DESCRIPTION - Harvesting Chlorella comprises adopting foam separation device, which includes a compressed nitrogen tank, buffer bottles, gas flow meter, bubble tower, gas distributor and collection bottle; where the compressed nitrogen tank outlet is connected to the buffer bottle inlet; the buffer bottle outlet is connected to gas flow inlet; the gas flow outlet is connected to the bottom of the bubble column gas inlet; the gas distributor is located at the bottom of the bubble column; the bubble column is provided with a feed inlet, and the lower part of the bubble column is provided with a discharge port; the bubble column outlet is product outlet; and the collection bottle is used for storing the final product discharged from the bubble column outlet; where the method specifically comprises: (i) adding surfactant into Chlorella raw material liquid, and adjusting the pH value; (ii) adding the obtained mixture into bubble column of foam separation device; and (iii) operating the foam separation device by opening the compressed nitrogen tank valve, then slowly opening the valve connected to the gas meter, adjusting the separated gas velocity, until the bubble column lower liquid color does not change, closing the valve and connecting the gas meter; then closing the compressed nitrogen tank valve until there is no bubble flow into the bubble column, and measuring the amount of the liquid collected in the collection bottle and bubble column, where the collected liquid is Chlorella suspension product.