Adult Ascaris lumbricoides is mainly parasitized in the upper part of human small intestine, and the female can lay about 200,000 eggs per day. The eggs discharged with feces will develop into infected eggs in about three weeks under the suitable temperature and humidity. Ascaris lumbricoides is mainly transmitted by mouth, infected eggs as the main means of transmission, if there is contaminated feces as fertilizer, vegetables and fruits are contaminated by eggs become the intermediate medium, eating raw fruits and vegetables without washing, scalding, eating raw unwashed vegetables, raw coleslaw, pickles and sauerkraut and so on will cause infection. In rural areas, casual urination and defecation can lead to ground contamination, children playing on the ground, sucking fingers, not washing hands before eating, eating while playing can lead to infection, drinking raw water can also lead to infection, and the eggs can also be swallowed and inhaled into the pharynx along with the dust.