Abstract: The emergency feedwater system (EFS) was served as one of the engineer safeguard system to remove the residual heat of the reactor coolant system. The flowrate test of postulated accident scenarios was the key role of the fuel loading licensing for the nuclear power plants. The system flowrates were found to be larger than the acceptance criteria in one certain plant during the system test. The criteria broken reasons were analytically investigated and the system retrofits were proposed by numerical simulation which was validated by the test data. The experimental data show that the system flowrates after system retrofits decrease and meet the requirement of the acceptance criteria.