The invention discloses an auxiliary decision-making method and system for six-prevention technical improvement investment of a power transmission line and a readable storage medium. The concept of profit and loss balance points in economics is used for reference, historical technical improvement data is used for fitting, a power transmission line technical improvement profit and loss balance yearis designed, and an optimal technical improvement measure aided decision scheme is obtained from objective historical data and a proposed mathematical model; the auxiliary decision scheme provided bythe scheme is objective and accurate, the technical improvement cost can be greatly reduced, and the technical improvement time is shortened.