Abstract: To examine the effects of biodegradable film mulching on soil moisture, temperature, salinity and yield of cotton fields, four kinds of biodegradable mulch films (T1, T2, JF, BSF) and ordinary PE mulch film (control) were applied in the oasis cotton filed of southern Xinjiang. We analyzed the roles of different biodegradable mulch films in preserving soil moisture, rising soil temperature, restraining soil salinity, and their effects on yield of cotton fields. The results showed that watersaving capability of BSF treatment was comparable to that of PE film, while that of T1, T2 and JF treatment was not comparable with PE film. The effect of restraining soil salinity of JF and BSF treatments was better than that of PE film, with mean salt content of 0-60 cm soil layer of JF and BSF treatments being 0.3 and 0.4 g·kg^-1 lower than that of PE film, respectively. The effect of restraining salinity of other treatments was lower than that of PE film treatment. Soil temperature in JF and BSF treatments was 0.3 and 1.6 ℃ higher than that of PE film treatment respectively, while that of other treatments was lower than that of PE mulch. Different biodegradable mulch films did not differ in their effects on ET_a, but significantly varied in their effects on the number of bolls per plant and water use efficiency. The earlier the mulch films degraded, the less number of bolls per plant, the lower water use efficiency. Seed cotton yield under BSF treatment was higher than that of other treatments, but was 20.2% lower than that of PE film treatment. Our results provide scientific support for the screening and safety evaluation of biodegradable mulch films in the study region.