The combinatorial etching technique based on photolithography has been used to fabricate step filters in this paper, in order to eliminate the size limit and shadow effect of mechanical masks. A step filter with 16\X1 channels for miniature wavelength-division device has been fabricated successfully. The width of a filter element is only 90 μm and the total size of the wavelength-division device is less than 2 mm. The filter channels distribute from 632.4 nm to 739.6 nm with bandwidth narrower than 2.9 nm and transmittance higher than 70%. The filter element size of the step filter can be as small as in micro scale and the shadow effect of mechanical masks can be decreased to micro or sub-micro scale. Such step filters match with CCD completely and can be used as miniature wavelength-division device to compose a miniature spectral system for space applications etc.