Abstract: 【Objective】 In order to clarify the appropriate amount of potassium fertilizer and its influence on the growth and development of millet in North Xinjiang, and to provide theoretical basis for high-yield cultivation of spring sowing millet in North Xinjiang. 【Methods】 Five kinds of potassium fertilizer (0, 75, 150, 225, 300 kg/hm²) were used in field tests with Yugu 18 as test material.Dry matter accumulation, chlorophyll content, internode fullness, agronomic characters and yield of millet were determined. 【Results】 With the increase of potassium application, agronomic indexes showed unimodal curve change, and the highest value was found in K₂₂₅ treatment.Compared with K0 treatment, plant height, ear length, ear diameter, stem base diameter, leaf length and leaf width were significantly increased by 8.1%, 26.1%, 20.9%, 22.6%, 12.9% and 9.4%.Compared with the control (0 kg/hm²), Yugu 18 was significantly increased by 1.2%-6.4% under potassium application, and the highest yield was 7,891.1 kg /hm² under 225 kg/hm² potassium application.(2) Compared with the control (0 kg/hm²), chlorophyll content increased significantly in each period after anther, showing a trend of first increasing and then decreasing, and reached the peak value under K₂₂₅ treatment.The dry matter accumulation showed a "J" shaped curve with the extension of growth period, and the dry matter accumulation rate showed a single-peak curve, and the maximum accumulation rate reached its peak from heading stage to full head stage.Moreover, the basal internode fullness increased obviously with the increase of potassium fertilizer. 【Conclusion】 the application of appropriate potash fertilizer has a significant effect on the growth and development of millet in northern Xinjiang, and K₂₂₅ treatment is the best application amount of potash fertilizer in Xinjiang.