86.64%、70.34%、79.69%、77.45%。 To control HC emissions of a gasoline engine under cold start an activated carbon absorber was developed to adsorb HC emissions. Coal based honeycomb activated carbon module was used as adsorbent. The absorber was encapsulated by welded metal sheets and the whole absorber was connected to the exhaust pipe in series. Cold start emissions test of a gasoline engine was performed to measure the HC emissions within 200 seconds after cold start. The engine test results showed that at the coolant temperature of 20,40,60 and 85 degrees centigrade the activated carbon absorber had the HC adsorption rate of 86.64%，70.34%，79.69%，77.45%.