The current highway tunnel budget quota is not suitable to make the budget of extralong tunnels. The author firstly analyzes the geological situations, construction scheme and originally designed quota of the main tunnel and ventilation shaft of Zhongnanshan Extralong Tunnel crossing Qinling Mountain in this paper. Then, the author studies the increased work days and machine shifts in the main tunnel construction and the problems related to the use of the coal quota to supplement the ventilation shaft quota. In the end, the author makes some suggestions on compiling quota for extralong highway tunnels.