Exhaust gas purification system for vehicle

A vehicle exhaust gas purification system and a control method thereof that may effectively remove nitrogen oxides in an exhaust gas even in a cold state, which is the initial stage of an engine starting, is disclosed. A control method of an exhaust gas purification system of a vehicle may include: a step of performing a rich control for controlling a concentration of non-combusted fuel contained in the exhaust gas flowing into the housing to be a rich fuel directly after the starting of the engine; a step of performing a lean control for controlling the concentration of the non-combusted fuel contained in the exhaust gas flowing into the housing to be a lean fuel; a step of determining whether a temperature of the exhaust gas flowing into the housing is a predetermined temperature or more; and a step of performing a normal control for controlling the concentration of the non-combusted fuel contained in the exhaust gas flowing into the housing so that a lean fuel and a rich fuel are periodically repeated with a regular interval.