To explore the effects of different tillage and straw returning patterns on soil fertility characteristics and peanut yield in upland red soil, a long-term fixed-site experiment was initiated in 2015 in Jinxian County, Jiangxi Province. A total of six treatments were established: rotary tillage without straw (RC), rotary tillage with straw mulching (RSF), rotary tillage with straw burying (RSD), plow tillage without straw (PC), plow tillage with straw mulching (PSF), and plow tillage with straw burying (PSD), and their effects on topsoil physical, chemical, and biological properties, and peanut yields were studied. The results revealed that, compared with RC, PC increased peanut yield by 4.20%. Compared with RC, RSF and RSD significantly increased peanut yield by 24.62% and 37.31%, respectively. Compared with PC, PSF and PSD significantly increased peanut yield by 34.34% and 41.67%, respectively. Compared with rotary tillage, plow tillage significantly increased topsoil depth (by 68.02%) and available topsoil volume (by 59.09%). Straw returning patterns primarily influenced soil physical environment by reducing soil bulk density (by 2.63%-9.02%) and increasing capillary porosity (by 10.85%-101.25%), while also significantly enhanced macro-aggregate content. Straw returning significantly increased soil nutrient contents including organic carbon, total nitrogen, total phosphorus, alkali-hydrolyzable nitrogen, available phosphorus, and available potassium (P<0.05), while also significantly enhancing soil enzyme activities and microbial biomass carbon/nitrogen contents (P<0.05). Among these practices, PSD demonstrated the most pronounced improvement effects. The integrated soil fertility index (IFI) reached 0.71 under PSD, increased by 26.79%-255.00% compared to other treatments. Correlation analysis revealed significant positive correlations between peanut yield and soil chemical fertility indexes, biological fertility indexes, and IFI (R²≥0.70). In summary, plow tillage with straw burying (PSD) is the optimal management practice for improving soil physical properties, enhancing overall soil fertility, boosting soil enzyme activities and microbial biomass carbon/nitrogen, and promoting peanut yield in upland red soil systems.