The invention belongs to the technical field of agricultural insecticides, and particularly relates to a fertilizing and molluscicidal double-effect organic fertilizer molluscicide and applications thereof, and aims to provide a plant-derived quaternary amine benzophenanthridine alkaloid organic fertilizer type molluscicide which has both molluscicidal effect and growth promoting effect on rice inrice fields. The optimal ratio and a preparation method of an alkaloid and an organic peptide fertilizer are provided. The fertilizing and molluscicidal double-effect organic fertilizer molluscicideis capable of avoiding using of chemical fertilizers and chemical molluscicides, and plays an extremely important role in solving the toxicity of the chemical molluscicides to aquatic fishes and the pollution and harm of the chemical fertilizers. The fertilizing and molluscicidal double-effect organic fertilizer molluscicide provided by the invention is prepared from the following components: quaternary amine triphenanthridine alkaloid with the concentration of 7.5-35mg/L; a potassium peptide fertilizer with a volume ratio concentration of 1ml/L-40ml/L; and a synergist with a volume ratio concentration of 0.1%-2%.