Abstract: Due to their strong target specificity, easy degradation, no residue, no pollution to the environment and other advantages, plant-derived insecticides have become an important area of development for green insecticides. As the most structurally diverse functional components of plant secondary metabolites, alkaloids exhibit broad-spectrum insecticidal properties and low ecotoxicity by interfering with nerve conduction and inhibiting metabolic enzyme activities. In this paper, we systematically summarize the structure optimization strategy based on the molecular skeleton of alkaloids, and focus on analyzing the structure-activity relationship (SAR) of typical alkaloids, such as pyridines, quinolines and quinolizidines, in terms of functional group modification and heterocyclic ring fusion, to reveal the intrinsic association between the spatial arrangement of the key pharmacophoric groups and the insecticidal activity. Meanwhile, with the development of molecular docking and target protein analysis technology, the insecticidal mechanism of this class of compounds has also been elucidated, such as neurotoxicity through competitive binding to chitinase or glutamate (Glu)-γ-aminobutyric acid (GABA) regulatory system and other targets, or by interfering with enzymes related to insect growth and metabolism to produce chronic physiological inhibition and other modes of action to exert insecticidal effects. The results of this study not only provide theoretical basis for rational drug design based on natural alkaloidal lead compounds, but also clarify the mechanism of action of alkaloidal insecticides, which will promote the research and development of plant-derived alkaloidal insecticides in the direction of precision and intelligence.