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In this study, we investigated the combustion technology for the direct injection (DI) methanol engine for a heavy-duty vehicle that makes use of the fuel characteristics of methanol and achieves smokeless burning with high efficiency and low NOx emissions under the heavy load condition. A 3.3-liter 4-cylinder spark-assisted DI methanol engine was tested to investigate the combustion and NOx emission characteristics under the full load condition with supercharging and/or EGR. We believe that supercharging suppressed the stratified charge combustion, but accelerated the premixed combustion to increase the indicated mean effective pressure. Moreover, supercharging was helpful in carrying out EGR under the full load condition without deteriorating the thermal efficiency. Furthermore, heavy EGR during supercharging reduced the NOx emissions dramatically while maintaining the high thermal efficiency and controlling the unburned hydrocarbons emissions.