The stacked geotextile structure is being increased as a structure for protecting beach line and as a structure for the purpose of solving environmental problem as well a dike. Three types of the geotextile tube were proposed to satisfy the desired crest height, structure for is being increased as a stand their stability against external forces was analyzed at each of the cross sections of the stacked geotextile tubes. The considered external forces were wave force, tidal force and lateral earth pressure by reclamation. Also, various field monitoring instrumentations (strain gauge, earth pressure cell, pore pressure measurement, inclinometer) were installed at a representative geotextile tube section. The behavior of a stacked geotextile tube was analyzed using field monitoring results, such as the tube structure settlement, the vertical soil pressure at the bottom of the tube, the lateral earth pressure, the surface strain of the geotextile tube, during and after construction. The analysis results showed that the stacked geotextile tube had external and internal stability. The seepage analysis showed that ground seepage was steady during monitoring. Therefore, when a temporary dike structure with a filling material is constructed, not only should its structural stability be considered, but also its height reduction due to settlement by low - pressure filling, scouring by high-velocity tides, and fine material loss by water flow. In this study, the experimental results of the behavior of stacked geotextile tubes are confirmed using a numerical method. Thus, by analyzing the behavior of stacked geotextile tubes at a coastal area by a numerical method such as FLAC, we can improve the geotextile tube technology for safe construction of structures at a shore.