Abstract: In order to achieve the spectral minimum resolvable temperature difference (MRTD) testing of infrared multispectral imaging and obtain more information of target and background, an acoustooptic tunable filter (AOTF)based multispectral static performance testing platform was designed and developed. At 3 m~5 m waveband,through adopting the designed optical testing platform,the subdivision of band was carried out in middlewave infrared region,and the MRTD tests were finished in targets with different spatial frequencies of 2.546 lp/mm,1.273 lp/mm,0.849 lp/mm and 0.632 lp/mm,respectively. The experimental result shows that, the test results of spectral MRTD correspond with the theoretic analysis,verifying the reliability of the optical testing platform and the feasibility of the testing method.