The chlorophyll meter can instantly measure the relative chlorophyll content (unit SPAD), greenness, and leaf temperature of plants, thereby understanding the plant's true nitro demand and understanding the lack of nitro in the soil or whether too much nitrogen fertilizer has been applied. This instrument can be used to increase the utilization rate of nitrogen fertilizer and protect the environment. It can be widely used in agricultural and forestry-related scientific research units and universities to conduct research on plant physiological indicators and guide agricultural production.