The secondary lining cancellation in the ventilation inclined shaft of highway tunnel has an impact on the stability and ventilation of the cavern. In order to solve this problem, the #1 inclined shaft of Qinling Tiantaishan tunnel is taken as an example to analyze the safety issue on the shotcrete lining of surrounding rock of this section of the cavern after the secondary lining cancellation according to the stratum characteristics and construction conditions of the grade Ⅲ surrounding rock section and considering the aspects such as specification requirements, structrual safety and durability.

 Meanwhile,  according to relevant specifications and literatures,  the frictional resistance coefficient along the route of the lining section of the surrounding rock shotcrete of grade Ⅲ inclined shaft is modified, and based on this analysis, the pressure loss of the tunnel air duct is calculated. A comprehensive comparison is made with the relevant parameters of the original design to reduce project cost under the premise of meeting the design requirements of the tunnel ventilation system. The results show that: (1) In the section with good geological surrounding rock condition, when it meets the specification, the cancellation of the secondary lining in the inclined shaft has sufficient safety margin. (2) In the inclined shaft, the wall surface roughness of the shotcrete lining does not exceed 30 mm, and the ventilation amount increase by 10% of the design air volume surplus of the equipment can offset the adverse effect of the cancellation of the secondary lining in the inclined shaft section on the pressure loss in this section.