The invention discloses a multiphase flow simulation test device for a refined oil product with water and impurities. The device is used for performing a simulation test on movement and deposition state of the refined oil product with water and impurities in an undulated pipeline and monitoring corrosion in the pipeline due to water and impurity accumulation. The device mainly comprises ten parts including an oil storage system 1, a power system 2, a flow adjusting and monitoring system 3, a drainage system 4, a filling system 5, an undulated pipeline testing system 6, a settlement separation system 7, a data acquisition system, a support system and an anti-static system. Besides, the invention further provides a method for performing testing by utilizing the multiphase flow simulation test device for the refined oil product with the water and the impurities.