The utility model discloses a stress corrosion resistance long term performance detection device for a carbon fiber composite cable, which comprises a glass steel tube (1) for the connecting of the connecting hardware fittings (2) at the two ends of the carbon fiber composite cable and resistance strain gages (3) a display and a control system (4) pasted on the carbon fiber composite cable, and screw stopples (5), which is used for the detecting of the pH value of acid solution, is formed in the upper part of the glass steel tube (1). The detection device provided by the utility model is reasonable in structural design, can flexibly adjust and detect the concentration of acid solution, is convenient to operate and high in detecting efficiency, can provide dependent variable under the action of tensile stress of carbon fiber composite cable in acidic or alkaline conditions, and can compute the load that the carbon fiber composite cable bears in acidic or alkaline conditions after many years according to the relationship between each data.