Exampled with the project of front slope for Deng cao-tang tunnel outlet, the front slope is treated with prestressed anchorage cables. The reason of front slope cracking is analyzed. Moreover, the stress distribution of anchorage cables has been monitored so as to obtain the stress distribution in time. The results offer scientific basis with the treatment effect of front slope so that the safety of tunnel construction in ensured. The study has been great theoretical significance and practical value.