The successful development of coal-based integrated gasification combined cycle (IGCC) technology requires gas turbines capable of achieving the dry low nitrogen oxides (NOx) combustion of hydrogen-rich syngas fuels for low emissions and high plant efficiency. Mitsubishi Hitachi Power Systems, Ltd. (MHPS) has been developing a “multiple-injection burner” to achieve the dry low-NOx (DLN) combustion of hydrogen-rich syngas fuels. The purposes of this paper are to present the test results of a multican combustor equipped with multiple-injection burners in an IGCC pilot plant, and evaluate combustor performance by focusing on the effects of flame shapes. The syngas fuel produced in the plant contained approximately 50% carbon monoxide, 20% hydrogen, and 20% nitrogen by volume. In the tests, the combustor with slenderer flames achieved lower NOx emissions of 10.9 ppm (at 15% oxygen), reduced combustor liner and burner plate metal temperatures, and lowered combustion efficiency at the maximum gas turbine load. The test results showed that the slenderer flames were more effective in reducing NOx emissions and liner/burner plate metal temperatures. A comparison with the diffusion-flame combustor demonstrated that the multiple-injection combustors achieved the dry low-NOx combustion of the syngas fuel in the plant.