The present disclosure relates to a valve opening control apparatus and method of a gasoline EGR system. The valve opening control apparatus includes a gasoline engine generating driving power through combustion, an intake line through which an intake gas flows into a combustion chamber of the gasoline engine, an exhaust line through which an exhaust gas is discharged from the combustion chamber, a recirculation line branched off from the exhaust line and connected to the intake line, an EGR cooler, positioned in the recirculation line, cooling the exhaust gas flowing in the intake line, an EGR valve configured to control an amount of the exhaust gas flowing in the intake line, an emergency (EM) filter positioned in one end of the EGR valve, and a flow rate regulator configured to control an opening amount of the EGR valve according to a clogging state of the EM filter.