The invention discloses a high polymer grouting reinforcement and water prevention three-dimensional protective structure for a cutting. The high polymer grouting reinforcement and water prevention three-dimensional protective structure is characterized in that a pavement protective structure is formed by paving a high polymer rubble waterproof layer, a waterproof plate, a buffer transition layer and a pavement layer on a foundation from bottom to top; a cutting side slope protective structure is formed by laying an earthwork pipe network on a cutting side slope; and high polymer grout is grouted into the earthwork pipe network through grouting pipes to form a grouting earthwork pipe network or grouted into column holes formed in the cutting side slope through grout-flow pipes to form multiple rows of reinforcement columns arranged upward from a slope toe along the cutting side slope at intervals. According to the high polymer grouting reinforcement and water prevention three-dimensional protective structure, pavement structure corrosion due to underground water reverse-permeation can be effectively prevented for a long time, side slope soil is reinforced, the side slope is made more stable, the stability of the side slope in the construction process is ensured, and security is provided for the safety of constructors.