Sorghum (Sorghum bicolor (L.) Moench) is a crucial crop in southwest China, supporting grain supply, animal feed, and the brewing industry. However, rain-fed production in the region is constrained by seasonal drought and high summer temperatures. A three-year field experiment (2020-2022) was conducted in a typical rain-fed sorghum production area of Guizhou Province, using a randomized complete block design with three treatments: (i) alternate whole-straw mulching (ASM), (ii) ridge film mulching (RFM), and (iii) traditional non-mulching (NM, control). The effects of these practices on soil hydrothermal conditions, water use efficiency (WUE), agronomic performance, yield, and economic sustainability were systematically evaluated. Results showed that compared with NM, ASM reduced the root concentration layer (5-20 cm) temperature by 1.1-1.4 degrees C, thereby alleviating heat stress during the critical stage of grain yield formation, whereas RFM increased temperature by 0.7-1.5 degrees C. Both mulching practices (RFM and ASM) significantly enhanced soil water storage (SWS) 0-100 cm layer and WUE, compared with NM. Specifically, RFM increased SWS by 4.0 %-13.3 % and WUE by 16.2 %- 53.1 %, while ASM showed increases of 5.1 %-14.8 % and 3.3 %-32.4 %, respectively. Notably, the WUE improvement was more substantial in the drought year of 2022 (32.4 %-52.1 %) than in the normal rainfall years of 2020 and 2022 (3.3 %-17.1 %). This inter-annual variation was primarily driven by differential evapotranspiration (ET) patterns and grain yield responses. During normal rainfall years, ET under RFM and ASM was 4.1 %-9.6 % and 5.0 %-12.7 % higher than under NM, respectively. Conversely, during the drought year, ET was significantly reduced by 1.8 % under RFM and 5.0 % under ASM, respectively. Concurrently, the increase in grain yield relative to NM was greater in the dry year (RFM: 50.4 %; ASM: 25.8 %) than in normal years (RFM: 22.5 %- 26.8 %; ASM: 13.0 %-16.5 %). The key factor driving yield enhancement under alternate mulching were more grains per spike and greater 1000-grain weight. Economically, ASM improved net returns by 13.9 %-38.5 % (3323.6-3780.4 & YEN;& sdot;ha-1) and the output/input ratio by 2.9 %-14.6 %, while RFM decreased the output/input ratio by 0.8 %-19.2 % due to additional costs of plastic film and labor. Overall, the cooling and moisture-retaining effects of ASM contribute to optimizing water consumption patterns and promoting sorghum growth, ultimately enhancing crop yield. Our results suggest that ASM can be adopted for sustainable sorghum production in hot, drought-prone regions.