The invention discloses a motor rotation shaft dynamic seal structure. The motor rotation shaft dynamic seal structure comprises a motor, a cup-shaped fixing component, a cylindrical sealing end cover, a magnetic block A and a magnetic block B; the cup-shaped fixing component is coaxially fixed on the output shaft of the motor; a motor shell is sleeved with a connection sleeve at one end of the output shaft of the motor; the connection sleeve is fixed to the motor shell; one end of the connection sleeve, which is far away from the motor, is provided with the cylindrical sealing end cover; a circular groove is formed at the inner wall surface of the cylindrical sealing end cover; a cylindrical groove which is coaxial with the cylindrical sealing end cover is formed at the outer side surface of the cylindrical sealing end cover; the cup wall part of the cup-shaped fixing component is inserted into the circular groove; the magnetic block A is fixed to the cup wall inner side of the cup-shaped fixing component in the circular groove; a fixing shaft which is coaxial with the cylindrical groove is fixed in the cylindrical groove of the cylindrical sealing end cover; a working shaft is matched with the fixing shaft through a bearing; and the magnetic block B is fixed to the outer side surface of the working shaft. The motor rotation shaft dynamic seal structure of the invention has the advantages of great sealing effect, suitability for high-speed rotation, high-and low-temperature harsh environments and long service life.