The invention provides an oil gas pipeline leakage detection method and system based on excitation response. The system is characterized in tha an active excitation signal (mutually directly inputtinga pressure pulse) or a passive excitation signal (pressure fluctuation is generated by a fast switching valve and the like) is applied to an oil gas pipeline with an existing leakage point, wherein the excitation signal is reflected at the boundary and the leakage portion of the pipeline, a reflected wave continues to transmit upstream and downstream and finally is collected by a dynamic pressuresensor; and existing leakage of the pipeline is detected and positioned by analyzing a transient response signal and the leakage signal reflected wave.