Abstract: An experimental study was conducted on the combustion and emissions characteristics of dualfuel SCCI on a singlecylinder engine, applying the portinjection nheptane and incylinder direct injection isooctane. Twostage combustion of homogenous charge of nheptane and air before top dead center ignites the isooctane, so the SCCI could achieve a staged combustion. The effects of the load and premixedratio were explored. The test result shows that SCCI offers good potential to expand the operating range, because the value of IMEP is up to 0.73 MPa when the maximum pressure rise rate is 0.87 MPa/(°). Operating points with high NOx emissions have the most nheptane amount of portinjection. Meanwhile, when the nheptane amount of portinjection is fixed, increasing the isooctane amount of direct injection can lower the CO and THC emissions.