Advanced Small Modular Pressurized Reactor (ACP100) is a new integrated small-scale reactor. Its once-through steam generators and reactor coolant pumps are directly integrated into the pressure vessel, and the compact design leads to a complex internal flow field. A 1/3 scaled-down model was used to simulate the entire internal flow field of the ACP100 reactor and carry out integral hydraulic simulation cold experiment for the reactor. In the experiment, the total pressure drop and segmented pressure drop of the model were obtained, as well as the total resistance coefficient and the segmented resistance coefficients of the main flow paths. The flow distribution factors of each fuel assembly at the core inlet were also acquired. The experiment results showed that the flow inside the main channels had entered the second self-modeling zone, and the flow pattern, velocity distribution and resistance coefficient of the fluid were consistent with those of the prototype reactor. After entering the second self-modeling zone, the total resistance coefficient of the model remained constant at 8.02, which can be used to calculate the pressure drop of the prototype directly. Under rated operating condition, all the distribution factors at the core inlet ranged from 0.91 to 1.08, meeting the design requirements. Besides, the flow distribution of LOFA simulation was uniform, indicating that the flow distributor had good rectifying effects. © 2023 Yuan Zi Neng Chuban She. All rights reserved.