Disclosed is a vapor splitter including: a chimney tray dividing an internal space of a housing into an upper space and a lower space; a chimney provided on the chimney tray to enable the upper space and the lower space to communicate with each other; a cap covering the chimney with a gap therebetween such that a gas discharge hole is formed so that gas, coming out through the chimney, can be transferred to the upper space through the gas discharge hole; a liquid feeding unit for feeding liquid to the upper space; and a liquid discharging unit for discharging the liquid out of the upper space. The size of the gas discharge hole is adjusted by controlling the height of the liquid collected on the chimney. Further disclosed is a method of adjusting a vapor split ratio using the vapor splitter.