Four-roll plate bending machines with high accuracy, high efficiency advantages are widely used in aerospace, instrumentation, pressure vessels, construction machinery and other fields. Due to the poor accuracy and low efficiency of plate bending process, the plate bending mechanism and precision control method are studied in this paper. Firstly, the plate forming mechanism and the bending process of the four-roll plate bending are analyzed. The calculation formula of plate bending springback is deduced by using elastic -plastic theory and mathematics model of plate bending is established. Secondly, the finite-element analysis model of the four-roll plate bending process is established based on ABAQUS simulation platform. The bending test is completed to compare the differences of the simulate radius, actual radius and the theory radius. The results show that it is feasible to use the simulation analysis method to develop plate bending craft parameter. Thirdly, theory analysis for the flexural deformation of the side roll is carried out. According to the two cases of single roll support and double rolls support, the calculation of the flexural deformation of the side roll is given. Based on these results, the specific scheme of the deflection compensation for the side roll is put forward. (C) 2017 The Authors. Published by Elsevier Ltd.