The load reducing method of the culvert with surrounding grouting and reinforcement is introduced to reduce the earth pressures and internal forces of highway culverts under high fills. Earth pressures and internal forces of the culvert with grouting and grouting covered with reinforcement are calculated by numerical simulations using finite element method, and the load reducing effects with different lateral grouting areas are compared. Additionally, the effects of geogrid stiffness, and the modulus of grouting on the earth pressures as well as internal forces of culvert are studied on the basis of parameter analysis. The results show that the grouting width surrounding the culvert wall is half of the culvert width, while the installation of geogrid reinforcement on the top of grouting area can further reduce earth pressures and internal forces. The increase of the geogrid stiffness makes very little effect on load reduction and the modulus in grouting area has a massive impact on earth pressures and internal forces. When the modulus is close to 100 MPa, earth pressures and internal forces reach at the lower values, which insignificantly decline as the increase of modulus.