The present invention relates to a novel cytisine derivative and a preparation method thereof and application thereof in pesticides for control of armyworm and Chilo suppressalis. The derivative is obtained by reacting of the cytisine with differently-substituted sulfonyl chloride according to the preparation method. Insecticidal activity tests prove that the derivative has a good control effectson test insects. The preparation process is simple, raw materials are cheap and easy to obtain, and the product has a high purity.