The utility model provides the novel structure of the sliding block part of a plate bender, which comprises a portal frame, a sliding block, a hydraulic cylinder, a guide rail and connecting rod units. Each connecting rod unit comprises two sets of first connecting rods, two sets of second connecting rods, two third connecting rods, and a hydraulic cylinder. Each set of the first connecting rods is composed of two first connecting rods. Each set of the second connecting rods is composed of two second connecting rods. Through improving the drive part of the sliding block, the active force is uniformly applied onto the top end of the sliding block. Therefore, the defect in the prior art that, under the effect of a concentratedly applied active force, the sliding block is heavily deformed to obviously influence the bending process of workpieces can be overcome.