黄河流域生态保护和高质量发展对水土保持提出迫切需求，泥沙持水能力是影响植被恢复与生态治理的关键因素。生物炭因其土壤改良与固碳潜力备受关注。通过生物炭改良技术，探究生物炭种类及粒径对黄河泥沙持水性能的影响。采用竹子、水稻壳、核桃壳、木质、玉米秸秆、玉米芯、芦苇等7个植物源的生物炭，0.05、0.18、0.5 ~ 1、1 ~ 3、3 ~ 5、5 ~ 8 mm共6个粒径梯度的竹类生物炭，掺入黄河泥沙中，形成生物炭与黄河泥沙混合样品。随后对混合样品的持水性能及微观结构进行试验分析。结果表明：生物炭粒径能够极大地影响黄河泥沙的持水性能，存在对黄河泥沙持水性能改良效果的临界值；生物炭种类对黄河泥沙持水性能有影响，且能够影响其粒径与持水性能的关系。微观结构试验显示：生物炭的加入优化了土壤的孔径分布，尤其是在40 μm处内的持水孔数量显著增加，增强了土壤水分吸附能力。然而，当生物炭粒径过小时，容易在土壤中形成团聚结构，将部分微孔完全填充，限制了持水性能的进一步提升。研究结果对实现碳封存和区域资源的新型利用提供了一定的理论依据。

The ecological protection and high-quality development of the Yellow River Basin raise urgent demands for enhanced soil and water conservation strategies. Sediment water retention capacity is recognized as a critical factor influencing vegetation restoration and ecological management. Biochar is widely acknowledged for its dual potential in soil improvement and carbon sequestration. To address regional challenges, a systematic investigation was conducted to evaluate the effects of biochar type and grain size on water-retention properties of Yellow River sediment. Seven plant-derived biochar types (bamboo, rice husk, walnut shell, wood, corn stalk, corn cob, reed) were selected, and six grain sizes of bamboo-derived biochar (0.05, 0.18, 0.5 ~ 1, 1 ~ 3, 3 ~ 5, 5 ~8 mm) were systematically tested. Composite mixtures were prepared by incorporating biochar into sediment. Water-retention characteristics were measured, and microstructural properties were analyzed through scanning electron microscopy. Results reveal that biochar grain size exerts a significant control over sediment water-holding capacity, with a critical threshold identified to maximize retention efficiency. Biochar type demonstrates a particle-size-dependent influence on water retention, where bamboo-derived biochar achieves optimal performance. Microstructure experiments show that the addition of biochar optimized the pore size distribution of soil, especially with a significant increase in the number of water holding pores within 40 μm, enhancing soil moisture adsorption capacity. However, when the particle size of biochar is too small, it is easy to form agglomeration structures in the soil, completely filling some micropores and limiting the further improvement of water holding capacity. The research results provide a theoretical basis for achieving carbon sequestration and new utilization of regional resources.