Waveguide-grating filters with single-layer and triple-layer thin-film structure were designed,which were based on the theory that reflected sidebands depressed more by introducing antireflection structures of thin-film into waveguide-gratings.The purpose was to obtain narrow linewidth and high peak response in wide spectral range by using layers as few as possible.Rigorous coupled-wave theory was used in precise calculation on the possible structures of single-layer and triple-layer thin-film waveguide filters,and good reflected curves were obtained.Furthermore,a good triple-layer thin-film structure which was easy achieved in experiment in wide spectral range was also obtained.