Based on gain compensation of stimulated Brillouin scattering

we study the wavelength characteristics improvement of microwave photonic filter and propose an improved method in this paper.If the gain spectrum of stimulated Brillouin scattering is overlapped with two loss spectra

the wavelength selectivity and bandwidth tunability can be achieved.Through calculation

the bandwidth is reduced from 20 MHz to 3.8 MHz

which reduced by 81% and wavelength selectivity is increased by 5times.In some special fields

the bandwidth can be further reduced through the cascade of filters.In this way

the bandwidth can be reduced from 13 MHz to 2.5 MHz

which reduced by 80.8%

and wavelength selectivity is further improved.Through simulation and experiment

it is proved that the method is practical and feasible.