Abstract: The procedure of advance protection against water hammer of products oil pipelines is generally implemented in the case of unplanned power failure of a pump station, which has a decisive influence on the safety of pipelines. To realize safe and smooth transition of pipelines from a steady state before the accident to a better operating state after the accident, an optimal scheme for advance protection against water hammer should be established. Water hammer conditions of product oil pipelines in the case of unplanned power failure of a pump station were analyzed. An optimization model was established with the objective of maximum throughput and minimum sum of throttling pressure of all regulating valves in the next steady state after water hammer accidents and under corresponding constraint conditions, i.e. no overpressure or vaporization throughout the pipeline. Two different strategies were used for model solution: translating hydraulic gradient line method for the downstream of the accident station through optimization with the objective of minimum outlet pressure of each station and depth-first search method for the upstream of the accident station through optimization of minimum total throttling pressure so as to improve the solving speed. The optimization model was applied in practice under the condition of a product oil pipeline in the case of unplanned power failure of a pump station. The control logic of the transient process in the water hammer accident was established based on the optimization result. Its rationality was verified by simulation software SPS which indicated the rationality and reliability of the optimization model.