The chirped electron-beam written phase mask is fabricated by step-chirped method.The step-chirped phase mask is a useful and powerful device to realize a nonlinearly or linearly stepwise chirped fiber grating with broad bandwidth.But the stitching errors of electron-beam written phase masks always occur between neighboring sections.The stitching errors can arouse the time delay ripple of chirped fiber Bragg gratings(CFBGs).The 140 mm CFBGs,which are written by using 2.0 mm,1.4 mm,1.0 mm and 0.5 mm stepwise chirped phase mask,have been studied by simulation and experiment.The best is the 1.4 mm step-chirped mask.The simulation agrees with the experiment well.