Increasing the air inflow can reduce the residual exhaust gas coefficient in the cylinder at low-speed and low-load,but would cause mixture too lean in opposed-piston two-stroke(OPTS)gasoline direct injection(GDI)engine.Focusing on this issue,the strategies of two-stage injection for stratified mixture at the typical part load(2000r/min)were studiedwith CFD software.The models for fuel the scavenging process and spray were verified by tests.Simulation results show that,there is an optimal second injection time forproper mixing,with early or late injection resulting in unreasonable mixture distribution,the best second injection time at 60℃ ATDC.Thefuel quantities of the second injection significantly influencesthe mixture formation,the second injection account for a third of total fuel quantities resulting in reasonable mixture distribution in the cylinder.