Objective To establish an ideal model of the mitral valve, including the left heart and blood, and study the motion characteristics of the mitral valve in blood flow using the fluid-structure interaction (FSI) simulation. Methods Based on anatomical parameters, models of the mitral valve, left heart, and blood were established. The finite-element combined immersed boundary method was used for FSI to simulate the motion of the mitral valve using the LS-DYNA software. Morphological, mechanical, and hemodynamic parameters were compared with those obtained from structural simulations. Results The morphological results of the mitral valve from the two simulations differed significantly, and the FSI results matched the ultrasound images. The stress distributions of the leaflets in the FSI and structural simulations were consistent. The maximum first principal stresses calculated by FSI and structural simulations were 1.48 MPa and 1.53 MPa, respectively, with a relative error of 3.27%. The fluid field in the left heart was complex with vortex structures, and the maximum mitral flow velocity was 1.02 m/s during diastole, consistent with the physiological data of healthy humans (0.89±0.15 m/s). Conclusions The morphological results of the mitral valve obtained from the FSI simulation were closer to those in the physiological state. FSI simulations can provide flow patterns that are indispensable for clinical diagnosis. Structural simulations are more efficient for studying leaflet stress distribution.