Animals that harm garden plants include insects, mites, snails, slugs, rat-wives, Ma Lu and so on. Among them, insects are the main ones, and there are many kinds of insects, mostly pests and beneficial insects, such as ladybugs, parasitic bees and parasitic flies. Therefore, it is necessary to distinguish pests from beneficial insects, restrain pests, and protect and utilize beneficial insects. In recent years, the prevention and control of garden pests and diseases has always followed the principles of agriculture and forestry, such as "early treatment, small treatment, treatment", "prevention first, active elimination". Because of "treatment" and "elimination", people think that "pesticides must be used for pest control" and "pesticides must be used for pest control", so the phenomenon of pesticide abuse is very serious, which destroys the natural ecological balance. It is suggested that the prevention and control of garden pests and diseases should follow the policy of "prevention first, comprehensive management" The prevention and control of garden pests and diseases should adopt effective methods suitable for urban characteristics, coordinate with each other, control the harm of pests and diseases, protect and utilize natural enemies, rationally use and gradually reduce the use of chemical pesticides, scientifically plant, maintain and manage from the ecological point of view, select disease-resistant varieties, restore ecological balance, strengthen plant quarantine, and carry out artificial prevention and control, so as to make the prevention and control of pests and diseases more scientific. Comprehensive prevention and control must be based on scientific planting, maintenance and management technical measures, and make full use of the objective laws of interdependence and mutual restriction among garden biological communities; Integrated control requires the coordination of biological control and chemical control, because organic connection is not contradictory; Comprehensive prevention and control, aiming at controlling pests and diseases, does not require the elimination of all left-wing consciousness. Eliminating it completely does not conform to the objective law of ecological balance.