The invention discloses a method for prolonging the harvest life of sugarcane by repeatedly replanting main stems of healthy sugarcane seedlings, the method comprises the following steps of: transplanting the healthy original sugarcane seedlings cultured by stem tip detoxification into a perennial root sugarcane field harvested in December or a sugarcane field newly planted in February next year for replanting after the seedlings are subjected to false planting and hardening, and when 90% of the healthy original sugarcane seedlings are tillered, cutting and transplanting the main stems to a perennial root sugarcane field harvested in January to February or a sugarcane field newly planted in March for replanting, and when 100% of the first cutting stems tillers, cutting and transplanting the main stems grown from the cutting stems to a perennial root sugarcane field harvested in March to April or a sugarcane field newly planted in April to May for replanting. By using the method, not only can the sugarcane seeds be saved, the cost of the sugarcane seeds used for replanting of the healthy sugarcane seedlings be reduced, the production period be shortened, but also the problem that the sugarcane are not replanted properly on a sugarcane field because the new planting period and harvesting period of the sugarcane are prolonged can be solved, and the harvest life of the sugarcane isprolonged.