Abstract: In order to research the conditions of full section excavation incomplicatedgeological conditions, choose the Ping-an tunnel of Chengdu-Lanzhou Railway as case study, based on the construction site investigation, establishment the fast evaluation system of rock physics mechanics parameters. Combine with the shear strength reduction and fast lagrangian methods, make a final judgement on suitability of full section excavation and prove the result. Theresearchshows: based on rockstrength parameter fast test, structure surface strength parameter fast test, structure surface rest angle test and GSI rock mass strength parameter test, the test results with the characteristics of fast, accurate and reliable; Under the premise of use the full section excavation, the safety coefficient is greater than the reference safety coefficient of surrounding rock in the case of grade IV rock, it indicates that the surrounding rock can undertake the stability requirements in full section excavation, the result of numerical analysis and field monitoring have strong consistency; Through the tunnel single cycle progress excavation optimization calculation, Ping-an tunnel single cycle excavate progress should be controlled in the range of 2.5m; Similar to the four typical tunnel surface rock mechanical parameters in that Ping-an tunnel of full face excavation is completely feasible.