The invention discloses a plant disease and insect pest control method. The method includes the steps of cultivation management, before-planting management, after-planting spraying of a green pesticide, scientific and balanced applying of an organic fertilizer, and planting of control plants. During the before-planting management, multiple purposes can be realized through one time of application by utilizing the strong oxidability of ozone water, control cost is low, labor and materials are effectively saved, and the problems of pesticide residual and environmental pollution caused by the application of pesticides are effectively solved; during the after-planting spraying of the green pesticide, the pesticide for control is formed by mixing pure natural plants, the control effect on the main plant diseases and insect pests is good, and a good environmental protection effect is realized by killing the plant diseases and insect pests through the green pesticide; the economic benefits, social benefits and ecological benefits are remarkable, the resistance of the plants is improved by applying the organic fertilizer, and the spreading of the plant diseases and insect pests is preventedby planting the control plants.