Experimental study on the compromise effects of injection parameters and coupled with EGR on combustion and emissions in a non-road common-rail diesel engine was conducted. Results show that fuel consumption and soot emission are decreased by increasing injection pressure and injection timing, but the NOX emissions increased, and the improvement of soot emission is not obvious when the rail pressure is 140 MPa. Rail pressure since 130 MPa, increasing 10 MPa every time, and injection timing since 6 ° CA BTDC, reducing 2 ° CA every time, adopting the strategy of synthetically adjusting injection pressure and injection timing can simultaneously optimizes the soot emission level and the NOX emission level, solving the shift problem of NOX emission and soot emission caused by single parameter adjusting, however the fuel consumption increased. Rdopting the strategy of EGR coupled with injection parameters can improves the soot emission and the NOX emission, as well as fuel consumption.