The invention discloses a green multifunctional air purifying device and method for removing haze and harmful substances. The air purifying device comprises a cylinder body, an axial flow fan, a Z-shaped air channel, spray heads, a water pump, aquatic plants, a plant growth light, a negative-ion generator and a transformer. A water curtain is formed in the Z-shaped air channel firstly, and indoor air passes through an air filter screen and then penetrates through the water curtain of the Z-shaped air channel. Ammonium nitrate and ammonium sulfate in the haze are dissolved in water through the water curtain and serve as nutrients of the aquatic plants to be reutilized, and harmful chemical compounds in the air can be absorbed by the plants; in addition, haze particles in the air can be absorbed by the water curtain, the green multifunctional air purifying device can release negative ions, and therefore four kinds of purification can be conducted on the indoor air through the air filter screen, the water curtain, the aquatic plants and the negative ions. The flowing time of the air in the device can be prolonged through the Z-shaped air channel, and therefore the air in the cylinder can be fully purified. Meanwhile, by means of the method, indoor air circulation is promoted, air humidity is improved, and therefore the indoor air quality is guaranteed, and the device is an ideal and completely green device which can remove the haze and harmful substances.