For over 20 years, highway slopes diseases frequently occured more and more in Zhejiang. An investigation on slope safety risks of highways which are in operation in Zhejiang was therefore conducted. The results show that most of highway slopes are safe, which only need routine inspections and maintenance. Part of the slopes need appropriate checks and inspections and timely prevention treatment. The proportion of type Ⅱ slope in soil slopes is 32%. This type of slope needs enhance security checks and inspections to prevent soil slopes of type Ⅱ from converting into Ⅲ class.