Abstract: Compared with the traditional accumulator, the advanced accumulator can automatically convert the flow rate in different periods of safety injection according to the core cooling need, which can increase the utilization efficiency of cooling water, and can simplify the safety injection system and save the construction cost. In order to achieve the hydraulic characteristics of the designed advanced accumulator, experiments were performed on the experimental loop designed based on similarity theory to eventually obtain the variation of relative data during injection period, including safety injection flow rate, pressure, liquid level, medium temperature and flow resistance coefficient of hydraulic component. The results show that the designed advanced accumulator test vessel can achieve the automatic conversion of flow, and the conversion ratio is about 3.5∶1, meanwhile the total injection time can reach 250 s, which has a certain advancement of safety injection performance index compared with the similar equipment. The results not only verify the advanced accumulator rationality of the structure design, but also provide input data for the reactor safety analysis.