Angular contact ball bearing has high rotation accuracy and limit speed, small friction and low temperature rise. It has certain rigidity but is not resistant to impact. It can bear radial and axial loads at the same time. The configuration methods include mounting in duplex, back to back(DB), mounting in duplex, face to face (DF), mounting in duplex , tandem (DT). The stiffness of the main shaft can be improved by pre-tightening. There are three contact angles of this type of bearing: 15?, 25? and 40?. The larger the contact angle, the greater the axial load capacity; and the smaller the contact angle, the more conducive to high-speed rotation. Single row bearing can bear radial load and unidirectional axial load; DB combination, DF combination and double row bearing can bear radial load and bidirectional axial load; DT combination is applicable to situations where unidirectional axial load is large and rated load of single bearing is insufficient.