To explore the effects of different tillage and straw returning methods on soil fertility characteristics and peanut yield in upland red soil, a long-term fixed-site experiment was initiated in 2015 in Jinxian, 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). The study investigated their effects on topsoil properties (physical, chemical, and biological) and peanut yield. Results revealed that during 2015-2021, compared with the RC treatment, the PC treatment increased peanut yield by 4.20%. Compared with the RC, Significantly greater increases of 24.62% and 37.31% were observed in the RSF and RSD treatments, respectively. Furthermore, compared with PC, the PSF and PSD treatments exhibited significant yield increases of 34.34% and 41.67%, respectively. Plow tillage significantly increased topsoil depth (+68.02%) and effective topsoil volume (+59.09%). Straw returning methods primarily influenced the soil physical environment by modifying soil bulk density (reduced by 2.63%-9.02%) and capillary porosity (increased by 10.85%-101.25%), consequently enhancing macro-aggregate content. Straw returning methods significantly increased soil nutrient indicators including organic carbon, total nitrogen, total phosphorus, alkali-hydrolyzable nitrogen, available phosphorus, and available potassium (P < 0.05), while also markedly enhancing soil enzyme activities and microbial biomass carbon/nitrogen content (P < 0.05). Among these practices, PSD demonstrated the most pronounced improvement effects. The integrated soil fertility index under PSD reached 0.71, representing increases of 26.79%-255.00% relative to other treatments. Correlation analysis revealed significant positive relationships between peanut yield and soil chemical fertility index, biological fertility index, and integrated fertility index (