Abstract: In view of impact on subgrade settlement induced by a frame bridge passing underneath a existing railway, a 2D numerical simulation model was established by ABAQUS software to analyze the patterns of ground settlement curves under different buried depths and different ratios of height and width, to study the calculation method for controlling criterion of subgrade settlement caused by a frame bridge underneath a existing railway, with the results showing that the subgrade settlement curves can be fitted by Peck formula; the coefficient of settlement trough width is corrected considering the linear relationship between i and B2 + htan ( 45° - φ2 ) ; the proposed subgrade settlement control criterion based on the requirements of track regularity control considers the cross-section width of the frame bridge, buried depth and internal angle of soil mass.