Abstract: With the development of space spectrum-imaging technology,long stripe assembled filter (assembled with narrowband filters) will be the key device to realize focal plane beam splitting in the future space spectral imaging system.This paper introduced the development of spectral imaging and assembled filter technology,and the long stripe assembled filter was developed.The design and deposition of 4-channel IR long stripe assembled filter were researched.Test results show a minimum bandwidth of 402 nm at 8.2 μm wavelength,and the average transmission rate was over 83%.Minus distance between narrowband filters was about 10 μm and the seam depth of parallelism between narrowband filters was only 2 μm.The assembled filter can withstand the test of space environment simulation and have been used in space now.