In order to reveal the pressure arch range of surrounding rock in deep buried unlined circular tunnel, based on the complex variable theory and the classical elastic-plastic theory and the M-C yield criterion, a method for accurately predicting the boundary of pressure arch is proposed. The correctness of the prediction method is verified by numerical calculation. On the basis of the correct prediction results, the sensitivity of the tunnel buried depth and lateral pressure coefficient and surrounding rock grade are discussed. The results show that: 1)The upper part of the deep unlined circular tunnel is the key to the construction of the tunnel, and the proper advance supporting measures should be taken to ensure the safety of the tunnel construction, and its support range should be more than 120°. 2) When the surrounding rock condition is poor, the tunnel construction urges the surrounding rock loose zone to run through, and it is necessary to take the full section ahead of grouting reinforcement measures to prevent the further development of surrounding rock loose zone. The research theory can provide reference to determine whether the loose zone around the tunnel penetrates through and to determine the position and range of the advance support.