Dual-band thermal emitters with narrow bandwidths are important in various applications in the infrared field， such as in infrared sensing and infrared imaging. However， conditions for narrowband emission in different wavelengths can conflict with each other， making it difficult to achieve dual-band emitter. In this paper， a new type of lithography-free infrared dual-band thermal emitter is proposed， which consists of alternately deposited Ge and YbF₃ films on Al films. The narrowband emission characteristics stem from the Tamm plasmon polaritons （TPP） that can be excited by the distributed Bragg reflector and the Al substrate under certain conditions. The geometric parameters are optimized using multi-objective particle swarm optimization. The experiment results confirm that dual-band emitter can simultaneously exhibit narrowband emitter characteristics in both mid-wave infrared （MWIR） and long-wave infrared （LWIR） regions. The proposed method can be used in the design of multi-band emitssion modulation applications， which can be applied in the fields of multi-gas sensing and multi-band infrared camouflage.