Abstract: Gravel packing has a wide range of sand control, not easily blocked and has a long sand control period for fine-silty sandstone and highly argillaceous reservoir and is used extensively. However, during gravel packing completion operations, there often occur such problems as packing opening not closed adequately, back-flow of packing sand, etc. Therefore, an anti-backflow gravel packing device has been designed which has three-layer sealing function. Field application shows that the improved tool has a 100% success rate of gravel packing, extended the maintenance cycle of oil wells, reduced capital investment in single wells and improved the economic profit.