As a powerful 3D collaborative design software, CATIA has been widely used in the field of water conservancy and hydropower engineering. The design of access road and construction road is an important part of the 3D collaborative design of water conservancy and hydropower engineering. According to the access road modeling of a Hydropower Station, this paper introduces a method of building 3D road model by using CATIA software, which is based on the results of two-dimensional design.