Abstract: The Mariana Trench is an important area in the evolution of the trench arc basin tectonic system in the Western Pacific Ocean. The study of the characteristics of the Mariana Trench is helpful to understand the differences in the formation and evolution of the trench parts. Based on the sediment and water depth data in the study area, the initial subduction dip angle (β₀) and the axis flexion (w₀) of the trench were calculated, the lithospheric flexion of the Mariana Trench was simulated, and the lithospheric effective elastic thickness (Te) of the Mariana Trench was obtained. The results show that the flexural position of the Mariana Trench is about 40～125 km, the flexural amplitude w_b is about 60～840 m, the effective elastic thickness is about 5～40 km, the initial subduction Angle β₀ is about 0.5°～5°, and the flexural w₀ of the axis is about 1.3～4.7 km. The effective elastic thickness of the middle trench is the highest, and the effective elastic thickness of the northern trench is slightly higher than that of the southern trench. The middle part of the trench is invaded by a large number of seamounts of different sizes, and the range of deflection, effective elastic thickness, initial subduction dip angle and deflection of axis are very large. The axial flexure of the southern segment of the trench is much higher than that of the northern segment and the middle segment, which may be related to the effect of the subduction of Caroline ridge and Caroline hot spot. There is no obvious correlation between the initial subduction dip angle and effective elastic thickness, deflection position and axis deflection.