The industrial robot bonnet polishing platform can not only meet the requirements of high efficiency and precision of optical polishing, but also reduce the system cost. It is a promising polishing equipment solution. The most practical method to improve BP material removal efficiency is to increase the contact depth. It is generally believed that the profile of the TIF of BP is Gaussian like distribution traditionally, but it is found that it actually changes into M-shape obviously with large contact depth. However, the existing reports on the TIF of bonnet polishing are mostly based on the Gaussian like TIF model which cannot accurately describe the M-shaped TIF. Therefore, according to the material characteristics of inflatable rubber bonnet, this paper establishes a new model to explain the changes of pressure distribution caused by large contact depth. Furthermore, a bonnet polishing approach based on dual- mode contact depth TIFs is proposed in order to improve the removal efficiency in rough polishing stage and increase the convergence accuracy in fine polishing stage.