Abstract: The core inlet flow distribution is essential in the study of the hydraulic performance of the reactor, which is closely related to the heat flux of the core and the flow induced vibration of the fuel assembly, and finally affects reactor operating limits. CAP1400 core inlet flow distribution experiment is an important step in the design and analysis of the CAP1400 reactor’s structure to verify the uniformity of the CAP1400 core inlet flow distribution. The experiment was performed with 1/6 linear scaling ratio model. The CAP1400 core inlet flow distribution was identified by non even-flow distributor and three conditions with even-flow distributor including balanced four-cold leg flow condition, unbalanced four-cold leg flow condition and extremely unbalanced condition with an assumption of a single pump failure. The uniformity of the CAP1400 core inlet flow distribution under different conditions was analysed. The experiment results show that the CAP1400 core inlet has a very good flow distribution.