The invention discloses a wave-shaped slab bridge underneath vehicle passing collision protecting device which comprises stand columns symmetrically arranged on the left side and the right side of a road bridge. Cushion plate are arranged at the upper ends of the stand columns. A height limit frame is fixed between the upper surface of the left cushion plate and the upper surface of the right cushion plate. The height limit frame comprises an upper steel plate, a lower steel plate and a wave-shaped plate. Two strips of symmetrically-arranged T-type steel are arranged between the upper steel plate and the lower steel plate. The upper surfaces of the transverse side edges of the T-type steel are welded and fixed to the lower side face of the upper steel plate. The lower ends of the longitudinal sides of the T-type steel are welded and fixed to the upper side face of the lower steel plate. The wave-shaped plate is arranged on the lower side face of the lower steel plate. The middle of the wave-shaped plate hunches downwards to form a height limit protection part. The lowest position of the height limit protection part is the maximum height limit position. The maximum height limit position of the height limit frame is provided with the replaceable wave-shaped plate, certain deformation is generated after scratching and collision occur, damage of the height limit frame is avoided, and the wave-shaped slab bridge underneath vehicle passing collision protecting device has good application prospects.