Abstract: To address the nutrient deficiency and severe degradation of yellow-red soils, this study investigates the effects of different biochar types and application rates on the physicochemical properties, extracellular enzyme activities related to the carbon and nitrogen cycles, aggregate composition, and carbon and nitrogen distribution in dryland yellow-red soils. The experiment included eight treatments: no fertilizer (CK), conventional fertilization (NPK), and conventional fertilization combined with the application of corn stover biochar, rice straw biochar, and pig manure biochar at application rates of 13.5 and 40.5 t/hm² (CSB1, CSB2, RSB1, RSB2, PMB1, and PMB2). The results showed that compared with the NPK treatment, the application of biochar significantly increased the soil organic carbon, total nitrogen, alkali-hydrolyzable nitrogen, and total potassium content, with increases ranging from 6.27% to 99.46%, 4.41% to 83.62%, 8.29% to 72.51%, and 2.84% to 15.51%, respectively. The application of rice straw biochar and corn stover biochar reduced the soil total phosphorus and available potassium contents, whereas the PMB2 treatment increased the soil total phosphorus, available phosphorus, available potassium, and cation exchange capacity by 7.65%, 76.42%, 14.23%, and 23.85%, respectively (P＜0.05). The application of biochars also significantly enhanced the activities of β-xylosidase, β-cellobiohydrolase, Leucine aminopeptidase, and N-acetyl-β-D-glucosaminidase, with increases of 29.36% to 78.84%, 51.91% to 265.03%, 4.16% to 149.80%, and 26.78% to 185.46%, respectively. The RSB1 and RSB2 treatments reduced β-glucosidase activity by 21.74% and 27.42%, respectively (P>0.05), while both corn stover biochar and pig manure biochar increased β-glucosidase activity. Except for the PMB1 treatment, which significantly decreased the 0.25-2 mm aggregate fraction by 35.00% (P＜0.05), other biochar treatments had no significant effects on this aggregate size fraction (P>0.05). The application of biochar did not significantly affect the 0.053-0.25 mm aggregate fraction (P>0.05). However, biochar applications increased the organic carbon and total nitrogen content of the 0.25-2 mm and 0.053-0.25 mm aggregates, with the PMB2 treatment showing the largest increases, by 129.54% and 25.22%, and 102.87% and 35.11%, respectively (P＜0.05). Furthermore, the PMB2 treatment also showed the largest increase in the organic carbon contribution rate of the 0.25-2 mm aggregates. In conclusion, the effectiveness of different biochar in improving the soil physicochemical properties and enzyme activities followed the order: Pig manure biochar, corn stover biochar, rice straw biochar, with PMB2 showing the best performance. The application of 40.5 t/hm² pig manure biochar is an effective strategy for improving the physicochemical properties, enzyme activities, and organic carbon and nitrogen content in aggregate in yellow-red soils and is highly suitable for soil improvement and fertility enhancement in dryland areas.