The invention discloses a single-anchor-cable-plate type foundation for a power transmission tower. The single-anchor-cable-plate type foundation for the power transmission tower comprises a bearing plate, an anchor eye, a pre-stressed anchor cable and concrete filled in the anchor eye. The pre-stressed anchor cable comprises a steel strand, a stretching and retracting anchor, a steel tube sleeve and steel cables. The stretching and retracting anchor comprises an upper connection plate, a lower connection plate, a spring connected with the upper connection plate and the lower connection plate and at least two connection rod assemblies symmetrically arranged on the two sides of the upper connection rod. The single-anchor-cable-plate type foundation for the power transmission tower resists vertically downward pressure, horizontal force and upward pulling force of the power transmission tower through the bearing plate and the pre-stressed anchor cable, the size of the anchor eye is reduced, the excavation amount of undisturbed soil and the spoil amount are reduced, the damage caused by large-area excavation to the environment is reduced, and therefore the ecological environment is protected. The invention further provides a construction method of the single-anchor-cable-plate type foundation for the power transmission tower. By the adoption of the construction method, during construction, the mechanical degree is high, the construction period is short, the construction efficiency is improved, and the construction cost is lowered.