In this study, series of experimental test were conducted on geocell type of reinforcements for its implementation to improve the strength of soft ground. The ground for test pit has less tensile strength than normal ground, which causes problems like subsidence of ground or weakening of bearing capacity. From the series of large soil box with geocell experiment varying filling materials and geocell shapes, the effect of geocell shape and filling material characteristics on bearing capacity of geocell reinforced soil layers was evaluated. Based on the result, reinforcement of bearing capacity and stress distribution effect of the sub-ground according to increase of loading was analyzed under the conditions including height, width, and shape of geocell, and types of filling materials. Evaluation of bearing capacity based on a large soil box test suggested that the ultimate bearing capacity with the maximum reinforcement increases by four to eight times in comparison with natural ground, and the largest ultimate bearing capacity is given in geocell shape of 1:1.2 (width: height) which is filled with sand, and to be 1:0.8 (width: height) when filled with sedimentary clay. Also, the maximum earth pressure in reinforced ground decreases 50% up to 60% in comparison with unreinforced ground because of dispersion of lower stress.