The self-aligning ball bearing has two structures: cylindrical hole and conical hole. The material of the cage is steel plate, synthetic resin and so on. Its characteristic is that the outer ring raceway is spherical and has automatic heart control, and it can compensate the error caused by different degrees of heart and axis deflection, but the relative inclination of inner and outer ring must not exceed 3 degrees. This kind of bearing is suitable for heavy load and impact load, precision instrument, low noise motor, automobile, motorcycle, metallurgy, rolling mill, mine, oil, paper, cement, squeezing sugar and other industries as well as general machinery.