Abstract: In order to study the effect of the detached eddy simulation model on the accuracy of hydraulic performance prediction for a nuclear main pump, with the hexahedral structured grid, the detached-eddy simulation (DES), delayed detached-eddy simulation (DDES) and improved delayed detached-eddy simulation (IDDES) based on SST κ-ω, were used to carry out the unsteady numerical simulation under full working conditions, and the calculation results were compared with that of RNG κ-ε model. The calculation accuracy of the four turbulence models was comprehensively evaluated from the aspects of relative calculation error and its dispersion. The results show that under full working conditions, the comprehensive calculation accuracy of each detached eddy simulation model is much higher than that of the RNG κ-ε model. The calculation accuracy of DDES and IDDES is almost the same under full working conditions, and is higher than that of DES model. The calculation accuracy of DDES near the design operation point is obviously better than that of IDDES. In comparison, the DDES model is more suitable for the performance prediction of a nuclear main pump.