Promising forward osmosis (FO) membrane desalination is a potentially viable energy-efficient performance technology compared to other techniques. Searching for the ideal draw solute that creates high osmotic pressure difference and ease of regeneration is critical for water desalination using the FO system. However, many fundamental aspects still need to be adapted, such as needing more screening potential anions and cations based on the predictive method. The Group Contribution Method (GCM) was used in this study to predict the value of the van’t Hoff factor denoted by (i). In the end, 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF4]) was selected as a draw solution for later experimental work.