As the main parts of the electric submersible pump, motor shaft is suitable for of 50 °C(C), 90 °C (A), 120 °C (E), 150 °C (F) four levels of oil-well temperature. Through continuous work, it keeps excellent sealing performance connecting with adapting piece. If single motor shaft can not meet the demand, the top sections or bottom sections can be combined into a series. After overspeed test, the motor shaft should have no permanent deformation and defects which obstruct the motor functioning.