In this study, we examined the techniques of optical effects employed by Le Nôtre at the garden of Vaux le Vicomte, based on reference materials and an on-the-spot survey. As a result, the following findings were clarified: Visual illusion of vertical gradient has caused from the difference in the drainage gradients of 2 flats. Viewed from the château, there are possibly two levels of vanishing point in perspective, contrary to the past studies; one for the Parterre in the foreground is at the clustered fountain (la gerbe) and the other for the area near the Triton Fountain in the back is at the Statue of Hercules. When viewed from the château, the horizontal angle to the surrounding structures including the grottos is approximately 14 degrees, giving the “picture” a sense of unity. Garden planning corresponded to the rather natural topography, not strict geometric application, readable from the topography and history of garden designing. One tends to imagine that the French garden is built on relatively flat land since it is also called a planar geometrical garden. In actuality, we reconfirmed an application of optical effects such as a three-dimensional treatment to the undulating land in order to make it look flatter.