Physical, mechnics and hydraulic properties of geotextile bags were studied in this paper by using scouring experiments. The results indicated as follows: For ecological bags with gravel or sand filler, the washout can cause the fine grain material filling into the gaps of geotextile, and thus, result in weight and thickness of unit area increase and the equivalent opening size O₉₅ is reduced. When flow velocity is 3.1-4.1m/s, the strength of geotextile bags with gravel filler is not obviously weakened in 3 hours, but partial damage will appear on bags and the strength is reduced by about 20% while the unity of the bags is unalterable. For ecological bags with sand filler, its strength and integrity is basically constant and partial damage is better than bags with gravel filler. However, heterogeneous deformation happens after 10-hour wash. At the terminal of the experimental flume with flow velocity 2.0 m/s, damages do not appear on the bags. By comparisons of physical, mechanics and hydraulic properties before and after the experiment, this proves that physical properties can not reflect the effect of wash on material characteristics. The mechanical properties such as tensile strength etc. are more suitable indicators to reflect the erosion-resistant characteristics of materials.