The invention discloses a distribution line power supply method and system. The system comprises an on-load tap changing transformer which is connected with a primary side circuit and a secondary side circuit, and is used for adjusting the transformation ratio of the primary and secondary side circuits; a passive compensation circuit which is disposed at the secondary side circuit; and a processor which is connected with the on-load tap changing transformer, and is used for determining the transformation ratio of the on-load tap changing transformer and the reactive compensation capacity of a reactive compensation circuit when the voltage of the primary side circuit and the voltage of the secondary primary side do not meet a preset condition, and adjusting the on-load tap changing transformer and/or the reactive compensation circuit according to a determined result. The invention solves a technical problem that a power distribution line causes the reactive power consumption in the related technologies so as to meet the requirements of electric energy.