The invention provides an agaro-oligosaccharide first, which is prepared by using agar to degrade an inorganic acid or an organic acid. The agaro-oligosaccharide is used for accelerating the degradation of fruit-vegetable pesticide residue. The raw material for agar used herein is derived from pure-natural marine algal polysaccharides; the agaro-oligosaccharide is free of environmental pollution, is friendly to food quality and safety, and is an environment-friendly good-safety biopreparation. The agaro-oligosaccharide is used to accelerate the detoxifying mechanism of fruits and vegetables themselves other than to degrade pesticides through compounds; therefore, the agaro-oligosaccharide is safer than existing techniques and has extensive effects.