This study aimed to investigate the effect of biochar application on the soil hydrothermal characteristics and three-phase structure in the cultivated layer of drip irrigated cotton fields during the non-irrigation season. Five biochar application amounts, 15 (B₁), 30 (B₂), 45 (B₃), 60 (B₄) and 0 (B₀) t/hm², were set to analyze their effects on the three-phase structure, total porosity, soil temperature and soil moisture content of topsoil (0-40 cm) in non-irrigation season of drip irrigation cotton field in Xinjiang. After the non-irrigation season, compared with the control, the soil solid volume decreased by 2.58%~10.74% and the total porosity increased by 3.38%~12.05%. At the same time, the soil moisture contents of carbon application treatments increased by 1.07%~2.65% compared with the control. The soil thermal conductivity decreased, and the soil thermal insulation effect increased. The minimum temperature of soil plough layer in non-irrigation season increased by 0.34~2.15℃,and the maximum temperature difference decreasedby 0.47~2.14℃. In addition, based on the above soil structure and hydrothermal characteristics of principal component analysis, the highest comprehensive score was B₃, followed by B₂. In conclusion, biochar application in non-irrigation season was beneficial to improve soil three-phase structure, increase soil total porosity and enhance soil moisture and heat preservation ability. The best application amount of biochar in non-irrigation season of drip irrigation cotton field in Xinjiang should be 30~45 t/hm².