<p>In the process of large-section tunnel construction, it is difficult to control the deformation of the surrounding rock due to the characteristics of large section span, shape close to flattening, and high requirement of the arch formation. The prestressed anchor support can improve the self-supporting capacity of the surrounding rock, which is an important means to realize the safety control of the surrounding rock in large-section tunnels. However, the prestressed anchor support is rarely used in large-section tunnels, and the control mechanism has not yet been clarified. Therefore, the author’s team carried out a numerical experimental study on the prestress control of large-section tunnels. The evaluation indicators for the effectiveness of surrounding rock control are established. The control effects of different prestress, bolt length, support density, surrounding rock strength and ground stress on the deformation of surrounding rock are analyzed. The control mechanism of prestressed support on the deformation of surrounding rock is clarified. The recommendations for the high prestress control engineering in large section tunnels are proposed. Based on the numerical experimental research, a field test of prestressed anchor support was carried out, which clarified the control mechanism of tunnel prestressed support. Monitoring results showed that, compared with the no prestress support scenario, the tunnel with 100 kN prestressed support had a maximum deformation of 28.4&#xa0;mm, reducing deformation by 36.3%. The utilization rates of bolts and arch frames were optimized from 5.9% and 90.2% to 44.3% and 53.1%, respectively. This research provides theoretical and technical support for optimizing the coordinated design of active–passive support, ensuring the safety control of tunnel surrounding rock, and reducing comprehensive construction costs.</p>