A plant imitating device includes a body having a compartment and an opening in communication with the compartment. A driving unit is mounted in the compartment and includes a transmission member. A plant imitating unit is mounted in the compartment and includes an end facing the opening of the body. The plant imitating unit is engaged with the transmission member by a mounting portion. The plant imitating unit is movable relative to the transmission member. A control unit is electrically connected to the driving unit. The control unit controls the driving unit to cause the end of the plant imitating unit to move beyond the body via the opening. Thus, the end of the plant imitating unit gradually extends beyond the opening to imitate the growth of a plant.