A diesel-gasoline dual fuel powered combustion engine system is provided with spark-assisted fouling free EGR system in which gasoline and air are homogeneously combined and supplied to cylinders and then a diesel fuel is injected and combusted together. The system may include: a plurality of cylinders each having a fuel injector; and an exhaust line through which flows an exhaust gas discharged as a fuel from each cylinder is combusted; wherein gasoline fuel combustion type is adapted to one or more cylinder of the plurality of the cylinders, and diesel-gasoline fuel pre-mixed combustion type is adapted to the other cylinders.