A forward osmosis process is provided, which includes separating a feed part and a draw solution part by a semi-permeable film. An ionic liquid is introduced into the draw solution part, and brine is introduced into the feed part. The brine has an osmotic pressure lower than that of the ionic liquid, so that pure water of the brine permeates through the semi-permeable film, enters the draw solution part, and mixes with the ionic liquid to form a draw solution. The draw solution was obtained out of the draw solution part to be left to stand at room temperature, so that the draw solution separated into a water layer and an ionic liquid layer. The ionic liquid includes;
