Abstract: Thrust is an important factor in shield construction safety during shield tunneling. In order to accurately estimate the thrust required during shield tunneling below the water level, the influences of water buoyancy on the force of shield tunneling are analyzed. The formula for calculating the shield thrust under the influences of water buoyancy is derived, and the relationship between the shield thrust and the torque is analyzed based on field measured data. The research results show that the deduced formula for the shield thrust can be in good agreement with the on-site shield thrust, and it can be used to calculate the thrust of the shield below the water level. The torque has a good linear relationship with the shield thrust, so the shield torque can be calculated through the thrust.