After budding of tobacco plants, a large amount of nutrients in the tobacco leaves flows to reproductive organs, which inevitably leads to a decrease in the yield of tobacco leaves and a decline in quality. In order to reduce the consumption of nutrients in leaves and increase the yield and quality of tobacco leaves, it must be topping up at the later stage of tobacco growth. After topping, the apical dominance of the tobacco plant was eliminated, and the tobacco axillary buds sprouted rapidly. Each axillary bud had the ability to flower and become strong. If the buds are not timely eradicated, the nutrients in the leaves will also be consumed, affecting the yield and quality of tobacco leaves. Therefore, the buds should be promptly wiped after the topping to control the growth of axillary buds. During the topping period, according to the topography, topography, plough depth and fertility level, nitrogen fertilizer application amount, and irrigation conditions of the production areas, the duration of the topping and the number of leaves per plant must be grasped. The upper leaves of the tobacco plants must be developed to have the same area as the middle leaf area. Slightly smaller to ensure the quality and usability of the upper leaves. Stuck to the top: When the bud is also wrapped in the top leaflet, carefully open the young leaves and remove the buds with tweezers or small bamboo sticks. This method has the earliest time for topping and consumes the least amount of nutrients, but it easily leads to the growth of the parietal lobe too thick, too thick, lack of elongation between the nodes, and the shortness of the tobacco plant. Generally only applies to tobacco fields with poor nutritional status and poor soil fertility, insufficient fertilization or poor soil fertility due to excessive rainfall, severe leaching of nutrients, etc. The purpose is to save more nutrients to concentrate the supply of leaves. Growth, thereby increasing the yield and quality of tobacco leaves. Budding: When the buds are 4-6 cm long, buds and young leaves have been clearly separated. At this time, buds and pedicels can be removed together with their lower 2-3 leaflets (also known as mosaics). This method has an earlier time of topping, less consumption of nutrients by the tobacco plants, full expansion of the parietal lobe, easy operation, and good results, and is one of the methods generally adopted in production. Initial flowering: When the top inflorescence extends from the parietal lobe and several flowers open, the entire inflorescence is removed together with its lower 2-3 leaflets. This method has a relatively long time to top, and nutrient consumption is more than that of budding. It is suitable for tobacco fields with adequate nutrition and strong soil fertility, and is also one of the commonly used methods in production. Full flower topping: When the inflorescence of tobacco plants spreads out, a large number of flowers are opened and the entire inflorescence is removed together with its lower 2-3 leaflets. This method has a late topping time and consumes too much nutrients, which is not conducive to the expansion of the parietal lobe. The top of the main stem is lignified and difficult to remove, and the wound is large and it is easy to infect diseases. Applicable to excessive nitrogen fertilizer or prolonged drought, fertilizer can not be fully absorbed by tobacco plants and excessive residual tobacco fields. The purpose is to allow the inflorescence to consume more nutrients (mainly nitrogen), so as to reduce the degree of nitrogen excess in the leaves, so that tobacco leaves mature at a proper time.