Abstract: Abstract: Plastic film mulching is an efficient way to improve soil water efficiency and heat effects, control salt and grass, and increase economic benefits in arid and semi-arid regions. However, with the overuse of traditional refractory plastic film, the residual plastic film is constantly increasing in the field, which has led to some negative impacts such as environmental pollution and land degradation. A kind of PBAT-based biodegradable film was introduced in this study and its effect on soil moisture, temperature and cotton yield was investigated. Field experiments under mulched drip irrigation were carried out from 2015 to 2016 in Xinjiang province, a typical arid region of China. A total of 5 mulching treatments was included: 1) ordinary PE plastic film (CK), 0.010 mm PBAT-based biodegradable film with designed induction period of 45 d (BD1), 0.010 mm PBAT-based biodegradable film with designed induction period of 60 d (BD2), 0.012 mm PBAT-based biodegradable film with designed induction period of 60 d (BD3) and 0.010 mm PBAT-based biodegradable film with designed induction period of 45 d (BD4). The soil temperature at 0-25 cm was measured and soil water storage at 0-100 mm was determined. The results showed that the biodegradable films began to degrade at 60-80 d after sowing and had net-like uniform crackers or 2-2.5 cm pieces at the harvest but was not degraded totally. Overall, all the biodegradable film started degrade after the designed induction period. Soil temperature at 0-25 cm was significantly lower by 0.94 and 1.34 ℃ (P<0.05) covering with 0.010 and 0.012 mm biodegradable films than the CK in the seedling stage of cotton, respectively. The difference of the temperature gradually reduced with the growing of cotton. All the mulching treatments could improve the soil water storage at the depth of 0-40 cm, but the water storage in the CK were higher than biodegradable film mulching in the late cotton growth stage because of degradation in biodegradable films (P<0.05). The 0.010 mm thickness biodegradable films (BD1, BD2 and BD4) were better than 0.012 mm biodegradable film (BD3) for the cotton yield. Compared with CK, the biodegradable film decreased the cotton yield of the 2 years by 2.89% on average (P<0.05) and reduced the water use efficiency by about 4%. For the economic benefit analysis, the cost of biodegradable film was higher and the net income of biodegradable film was 10.2% less than the CK. In sum, the biodegradable film still has big chance to improve its effect on yield and performance of improving soil temperature and moisture before it will be used to replace ordinary PE plastic film.