A field experiment of three treatments, i.e., traditional cultivation without mulching(CK), white plastic mulching(WM) and black plastic mulching(BM) was designed and performed to determine the effects of film mulching on soil temperature, water content, bulk density, and porosity and respiration rate in the 0-40 cm soil layer under Populus euramericana. Results indicated that the WM treatment had better warming effect than the BM treatment, but had no significant difference in the soil water content. In the 0-20 cm layer, the WM and BM treatments significantly increased the soil total porosity, capillary porosity and non-capillary porosity and however, the soil bulk density was visibly decreased, which was reduced by 15.44% and 9.56%, respectively. Besides, the soil respiration rate in the WM treatment had no significant difference as compared with CK, but the soil respiration rate in the BM treatment was obviously decreased. The 20-40 cm soil layer showed the variation trend similar to the 0-20 cm soil layer, while the differences among CK, WM and BM were decreased in the 20-40 cm soil layer, demonstrating that the effects of plastic film mulching on poplar weakened with the increasing of soil depth. In conclusion, the two plastic film mulching treatments significantly ameliorated the physical property of topsoil, while the black plastic mulching treatment evidently inhibited the soil respiration. Therefore, the white plastic mulching was obviously better than the black plastic mulching.