Linear variable filter adopts the continuous coating method and realizes the spatial continuous change of the filter characteristics based on the multi-layer wedge film structure. The target linear rate of change can be obtained by adjusting the slope of the film according to the dispersion requirement. Linear variable filter has high integrated spectral ability, which has irreplaceable advantages in the miniaturization and lightweight design of spectral instruments. Products are widely used in lightweight hyperspectral imaging spectrometer, portable spectrometer, medical endoscope.