Abstract: According to the distinguishing structure feature of three-lobe bearing with fixing pads,the influences of preload factor which is a key structure parameter on the lubrication properties,such as load capacity,attitude angle,stiffness coefficients and damping coefficients,were studied through solving the Reynolds equation numerically with program,and a series of conclusion between load capacity,attitude angle,stiffness coefficients,damping coefficients and preload factor are obtained.Preload factor are proved as an important factor to the three-lobe bearing.