The invention provides an aphidius gifuensis breeding method for controlling growth of host crops. When host tobacco seedlings grow to a certain stage, a plant growth regulator is sprayed first, and then myzus persicae is inoculated; when the myzus persicae grows to a certain number, aphidius gifuensis is inoculated. The plant growth regulator is introduced in the process of breeding the aphidius gifuensis through a method of breeding bees on seedlings. The method can effectively inhibit excessive growth of the tobacco seedlings, inhibit growth of leaves of the tobacco seedlings, enlarge gaps between the tobacco seedlings, improve ventilation and light transparency and have a certain promotion effect on reducing the local humidity around the leaves and improving the survival rate and vitality of the myzus persicae.