The invention relates to a one-way hydraulic diameter-expanding pipeline breakage simulation experiment device which comprises a pipeline supporting system, a pipeline expanding system, an oil incoming pipe and a DIC testing system. The pipeline supporting system supports two ends of an experimental pipe section, the side wall of the experimental pipe section is provided with axially-penetrating precracks which are symmetric according to an axial middle plane of the experimental pipe section, the inner end face of the pipeline expanding system is coincident with the axial middle plane of the experimental pipe section, incoming oil of the oil incoming pipe provides hydraulic power to the pipeline expanding system, and the DIC testing system observes the breakage process of the experimental pipe section in real time. A hydraulic driving device is adopted for an experiment, so that working risk is lowered, and cost is reduced; during the experiment, opening speed of a fan-shaped block and expanding speed of the cracks can be controlled by controlling moving speed of an extensible rod, so that accuracy of acquired data is ensured; the fan-shaped block is long enough and contacts with a pipe wall uniformly in the process of expanding, so that stable expanding of the cracks during the experiment is guaranteed.