Abstract: The pressure water reactor (PWR) with double loops exists abnormal operation mode with asymmetrical coolant flux and temperature on the inlet of reactor. The paper constructs a local three dimensional thermal-hydraulics model applying computational fluid dynamics (CFD) method and coupling with three dimensional neutron kinetics code. Using this model, a numerical simulation of the reactor neutron kinetics and thermal hydraulics behavior was realized on the asymmetrical reactor inlet condition. The coolant mixing inside the reactor pressure vessel was analyzed using CFD method in detail. The effects of dissymmetrical reactor inlet coolant flux and temperature on core coolant flux and neutron flux distribution were researched. The computational results were compared with the results computed by RELAP5 code. The results demonstrate that the reactor asymmetrical inlet condition sharply increases the heterogeneity of the core inlet coolant flux and temperature distribution, ulteriorly induces the heterogeneity of reactor power distribution, and finally results in the increase of core power distribution peak factor. It also can be concluded that the more accurate CFD method and three dimensional neutron kinetics code based on neutron diffusion method are necessary for steady-state and transient/accident analysis on reactor asymmetrical inlet condition.