For the roll bending characteristics of thicker plate and larger forming radius for thick plate components such as offshore wind turbine towers, a simplified model for roll bending process and a modified model considering the offset of bending neutral layer were established, and the roll bending process experiments were conducted. The research results show that the offset of bending neutral layer during the forming process leads to significant differences in the analysis results of contact angles and reduction amounts obtained by the simplified model and the modified model. The increase in the center distance between lower rollers leads to an increase in the contact angle and the reduction amount required to achieve the target radius, while the downward force decreases. Due to the influence of springback, the thicker plates with the same bending curvature require a greater reduction amount to form. With the increasing of plate thickness and reduction amount, the calculation results of the modified model considering the offset of bending neutral layer are in good agreement with the experimental reduction amount.