The present invention provides a large two-stroke diesel engine with an exhaust gas scrubber, wherein the water with high salinity is pumped to the exhaust gas scrubber for generating spray. The exhaust gas passes through the spray for reducing the content of SO2. The engine is also provided with a scavenging humidifying unit which is operated by sea water and/or a fresh water generator that converts sea water to fresh water. The high salinity waste water of the scavenging humidifying unit and/or the fresh water generator is used for the exhaust gas scrubber. Compared with the common sea water, the high salinity of the waste water increases the efficiency of the scrubber. Therefore, a considerably large pumping workload required for keeping the operation of scrubber can be remarkably reduced.