The complex structure of a pool-type sodium-cooled fast reactor may lead to uncertainty and asymmetry of flow and temperature field distributions under a pump stuck accident. This phenomenon has obvious three-dimensional (3-D) thermal-hydraulic characteristics and cannot be analyzed by one-dimensional or two-dimensional models. Previous research has been limited and lacking of 3-D numerical data. Therefore, the commercial computational fluid dynamics software FLUENT is used to simulate a full-scale 3-D integrated model of the China Experimental Fast Reactor (CEFR) in order to obtain 3-D thermal-hydraulic characteristics of key structures and components in the pool-type sodium-cooled fast reactor under a pump stuck accident in the primary loop. The results show that a special asymmetrical backflow phenomenon may occur in the pressure tube and the intermediate heat exchangers (IHXs) of the failure loop under the accident, further leading to complicated flow and thermal characteristics in both the hot and the cold pools. There is obvious thermal stratification and asymmetric temperature distribution, within a temperature difference of more than 90°C between the different loops’ IHX outlet. The temperature difference between the upper and lower areas of the baffles is 20°C to 105°C. This research provides a detailed reference for engineering design and operation.