Abstract: To examine the effects of biodegradable film on preservation of soil temperature, moisture, growth and yield of cotton fields in Hexi area of Gansu, the trials were conducted with four treatments of DA (biodegradable film A with thickness of 0.012 mm), DB (biodegradable film B with thickness of 0.008 mm), common plastic film and unmulching were used to analyze the changes of degradation property, soil temperature, moisture, weeds control, and yield in 2016 and 2017. The results showed that the induction period of DB was three to five days earlier than that of the DA and the degradation rate was higher than DA. The mass loss rate of DA and DB could reach 95.6% and 94.5% respectively under 180 days landfill treatment. The DA showed good performance in water retention, soil warming in seedling stage, with no significant difference with the common plastic film. Due to the high degradation rate, water retention property, and insulation of DB were significantly lower than that of common plastic film. The growth period of cotton prolonged by biodegradable film compared with common plastic film, but with no significant difference of the emergence rate, boll number per plant, boll mass and lint percentage. However, the pre-frost yield and weeds control effects significantly decreased. There was no significant difference of cotton yield of DA compared with common film, but significantly increased by 73.1% and 59.9% compared with unmulching. The cotton yield of DB was significantly decreased by 11.8% and 7.1% compared with common film. In summary, DA played good performance on the preservation of soil temperature, moisture and the yield increasing effect, which could be applied in Hexi agricultural area of Gansu.