Abstract: The mold bag method, as new dam construction technology, is used to solve the problem of dam upstream of fine-grained tailings. However, the theoretical and experimental researches on the mechanical properties are still needed to be further improved. The geotextile and tailings used in this paper are the same as that in a mine project. The interfacial friction direct shear studies of the consolidation of a certain number of days of the mold bag body and a certain degree of compaction of tailings with geotextile are carried out. The results of the friction test show that in the interface friction tests of different tailings with different compaction and geotextiles and the mold bag body with different filling degrees, the larger the degree of compaction and filling, the larger the interface friction angle. Due to the common function of the cloth and the tailings, the shear strength of the mold bag is much greater than that of the tailing shear strength. The results may provide guidance for examining the stability of the shear strength of the tailings filling mold bag.