The residual pesticide-reducing method shortens the half life and/or the complete degradation time of pesticide residue. During the whole growing period of crops or before seeding, the available mixture consisted of the pesticide preparation at 45%∼100% of normal dose and the synergistic agent is applied for at least one time as the conventional way, in which the ratio of the pesticide preparation and the synergistic agent is 15∼45000 g or ml/60∼6000 ml per hectare. The synergist is the mixture of Tween surfactants and N-R-2-pyrrolidone recorded in Chinese patent with the number 96117683.0. Under the precondition of ensuring potency, and determining the usage amount of pesticide based on the occurrence circumstances of invasive pests, the method of the present invention can reduce up to 55% dosage of pesticide, as well as the half life of pesticide residue and/or the complete degradation time by above 50%. After administration in safety interval, the pesticide residue in agricultural products can be "undetectable", effectively ensuring the quality safety of agricultural products and the protection on environment/ecology.
