A method for securing a bottom piece to a paper-made container forms first and second glue layers in one injection molding process. The method includes a mold set has a first concavity located corresponding to the open top of the paper-made container and communicating with a pouring path of an entrance via a first passage in the mold. A second concavity is defined in the mold and communicates with a second passage which communicates with the pouring path via a hole defined through the bottom piece. The two glue layers are formed within one molding process while the bottom piece is connected to the paper-made container.