Model parameters of conditioned soils in head chamber of shield machine are determined based on tri-axial compression tests in laboratory. The loads acting on tunneling face are estimated according to static earth pressure principle. Based on Duncan-Chang nonlinear elastic constitutive model, the earth pressures on head chamber of shield machine are simulated. The variation of earth pressure on different section in head chamber of shield machine is depicted. Relationship between pressure transportation factor and openings rotating cutter-head of shield machine is proposed by using aggression analysis.