Multi-band filter is the key component of the detector of space optical-remote-sensing camera. It was used for multispectral band-pass filtering and the encapsulation of detector. Because of the complicate feature sizes and films, the designing and environment adaptability assessment of multi-band filter were more complicated than the panchromatic or monochromatic filter. Physical dimension of filter substrate, filter window size, on-die pixel-location-symbol window size and on-filter alignment mark were the feature sizes of a multi-band filter, whose designing and calculating method for these feature sizes were given. Influences of designing or manufacturing error of the multi-band filter were also analysed, such as filter-and-die alignment precision, detector butting precision on focal plane assembly, and spectral response characteristic of camera system. An environmental assessment method for multi-band filter was also proposed, and the assessment method was based on the existing environment adaptability assessment standard for spacecraft. Finally an application example of multi-band filter designing and environmental assessment from some space camera was given.