The key to meeting the requirements of ever-tightening emission standards is improving the efficiency of exhaust conversion during cold-start. In order to reach the aim, a new method using microwave-heated catalysts is proposed in this paper. Preliminary testing results show that the three-way catalysts can be rapidly and uniformly heated using microwave-adsorbed ceramic foams as the substrate, and sufficient purification efficiency can be achieved with microwave-heated even under the conditions of low temperature of inlet gas, oxygen-lean, oxygen-rich and high space velocity.