Abstract ： Research purposes ： High and steep portals with unsymmetrical load of high speed railway in mountain area were prone to instability and collapse. How to safety into the tunnel was the focus and difficulty of the whole tunnel design. Taking design and practice of Hunan section tunnel on Shanghai - Kunming Passenger Dedicated Line as the background, this paper systematically studied the design concept and design principles in high and steep portals of unsymmetrical load. Meanwhile, this paper pointed out the integrated strengthening structural measures such as stay piles , protecting arch , ear - wall , prestressed anchor cable and frame beam , portal - structure and retaining structure , to ensure the safety of the bad tunnel portal. Research conclusions:( 1) Using the integrated strengthening structure - measures , such as stay piles , protecting arch , ear - wall , prestressed anchor cable and frame beam , portal - structure , retaining structure , strong supporting , can efectively solve the problems of the stability and safety of the high and steep portals with unsymmetrical load. (2) Using the design with inducing slope excavation and weak blasting and structural measures of organic combination such as portal , heading slope protection , retaining structure and local terrain and geological conditions , has been successfully applied to Hunan section tunnel portals on Shanghai - Kunming Passenger Dedicated Line and achieved the good effect. (3 ) The research results can be promoted and used when building the high and steep portals with unsymmetrical load of high - speed railway tunnels.