Abstract: Vegetable soybean varieties with high potassium (K) efficiency exhibit increased efficiency in K and dry matter utilization and partitioning. However, the partitioning and utilization of nitrogen (N) and phosphorus (P) in plants during this process are little known. This study aims to investigate potential differences in the accumulation and partitoning of N and P in vegetable soybeans under low K conditions based on different K efficiency types. Using various K efficiency varieties of vegetable soybeans and setting two treatments of low K 0 kg(K₂SO₄)·hm⁻², K0 and normal K application 120 kg(K₂SO₄)·hm⁻², K120, the study compared changes in N, P, and K concentrations and accumulation in both vegetative organ and seed of the plants, as well as their distribution patterns. Results indicated that low K levels reduce the accumulation of N, P, and K in the vegetative and reproductive organs of vegetable soybeans but increase the concentration of N and P in the vegetative organs. Furthermore, the low K condition reduces the K/N and K/P ratio of the vegetative organs, particularly in K high-efficiency varieties, but exhibits little difference in the seeds. Additionally, compared to K low-efficiency vegetable soybean varieties, the N/P in K high-efficiency vegetable soybeans is lower. The increased P relative content might be linked to improved root K uptake and nitrogen fixation. Notably, under the low K condition, the harvest index of N, P, and K is higher in K high-efficiency vegetable soybeans compared to K low-efficiency varieties. From a source-sink perspective, K high-efficiency vegetable soybeans prioritize ensuring nutrient supply to seeds through balanced nutrient utilization. This study offers a foundational reference for breeding nitrogen, phosphorus, and potassium synergistic high-efficiency vegetable soybean varieties.