A pool apparatus configured to carry liquids has a side wall and a bottom surface. The side wall has a plurality of structure drawstrings, an outer side wall, and an inner side wall. Two sides of the structure drawstrings draw respectively the outer side wall and the inner side wall, so as to maintain a predetermined shape of the pool apparatus. The structure drawstrings include a main drawstring portions and at least two branch drawstring portions. The main drawstring portions have a first main string side configured to connect a first branch drawstring side of the at least two branch drawstrings. A second branch string side of the at least two branch drawstrings connects respectively to different positions of the outer side wall and the inner side wall.