The invention discloses an automatic transmission gear self-learning method and a transmission control unit. A gear-shifting finger can be controlled to successively move to a left gear-selecting boundary point and a right gear-selecting boundary point of a gear to be learnt, and the midpoint of the left gear-selecting boundary point and the right gear-selecting boundary point is used as a gear-selecting position point obtained by learning; a gear-selecting position point of a gear to be learned saved in the transmission control unit is replaced with the gear-selecting position point obtainedby learning; the gear-shifting finger is controlled to successively move to a left gear-engaging boundary point and a right gear-engaging boundary point of the gear to be learnt, and according to themagnitude relationship between the distance from the left gear-engaging boundary point to the gear-selecting position point obtained by learning and the distance from the right gear-engaging boundarypoint to the gear-selecting position point obtained by learning, a gear-engaging position point of the gear to be learnt saved in the transmission control unit is replaced with the right gear-engagingboundary point or the left gear-engaging boundary point. The automatic transmission gear self-learning method and the transmission control unit realize the self-learning of the gear-selecting position point and the gear-engaging position point by controlling the movement of the gear-shifting finger, and the accuracy of gear switching is improved.