The invention provides a method and apparatus of adjusting off-limit electric quantity of a line. The method of adjusting off-limit electric quantity of a line includes the steps: calculating the initial off-limit electric quantity of the line and the off-limit electric quantity of a section; determining the off-limit electric quantity distributed to the line by the section and the final adjusted electric quantity of the line; and determining the adjusted electric quantity of a transaction unit, and updating the electric quantity of the transaction unit. The technical scheme of the method and apparatus of adjusting off-limit electric quantity of a line comprehensively considers the situation that off-limit of electric quantity is caused by transaction for the line and the section, and performs corresponding adjustment through the unit, thus having higher universality than a traditional method only considering and contacting off-limit of line. By taking the principle of lowest adjusted electric quantity of the line and minimum number of adjusting times, the method and apparatus of adjusting off-limit electric quantity of a line start adjustment from the maximum off-limit electric quantity and start adjustment from the unit with the highest sensitivity, thus guaranteeing minimum adjusting amplitude.