The invention discloses an active calibration type water supply pipeline leakage coherent detection method and device. The transmission speed of sound waves in a pipeline to be detected is measured inreal time, the actually measured wave speed is introduced into positioning calculation of a leakage point coherent detection instrument, and leakage point positioning errors caused by inappropriate setting of wave speed parameters can be reduced; an active calibration device is arranged in the system, can be used for self detection of the pipeline leakage coherent detection instrument, and therefore system positioning errors can be obtained. Accordingly, the instrument state performance can be effectively grasped through the self detection way in daily maintenance, and the effect that maintenance is convenient is achieved.