To meet the application requirements of multi-channel fine spectrometry of infrared detectors, pixel-level filters need to be accurately integrated on the cold head of infrared detector assembly, and the assembly accuracy of the filters in the X, Y and Z directions needs to be controlled within 10 μm to reduce the stray light interference between different channels. The pixel-level filter is designed based on a 320×256@30 μm mid-wave infrared detector. Four adjacent pixels on the detector are grouped together, and each pixel has its own absorption spectrum on the corresponding region of the pixel-level filter. By comparing and analyzing the spectral absorption curves of the four pixels when the adhesive and the metal filter bracket are respectively used as the supporting structure of the pixel-level filter, it is found that the Z-direction assembly spacing of the former can be as low as 2-10 μm, and the stray light absorption outside the cutoff band can be reduced by 25%-50% compared with the latter. The results show that the assembly process using adhesive as the micro-support structure of the filter can effectively solve the stray light interference problem of pixel-level filters.