In order to reveal the characteristics and evolution law of multiscale vortex flow field in water medium hydrodynamic coupling based on the CFD technique，four kinds of turbulence models ( DES，DDES，IDDES， LES) were used to simulate the internal multiscale vortex flow field of turbine in hydrodynamic coupling in braking and traction conditions． The flow images of internal flow field in turbine were collected by particle image velocimetry ( PIV) technology， static and dynamic image calibration methods were used to calculate the flow field under different conditions． The applicability of the four turbulence models was evaluated on the basis of the comparison of PIV experimental results． The results show that under the braking condition，the simulation results of multiscale vortex flow field in mainstream region used by LES turbulence model tend to be true， the flow velocity range is from 3. 52 to 3. 81m/s，and the vorticity range is from 480 to 540s －1． While the simulation results of multiscale vortex flow field in the near-wall region of the blade used by IDDES turbulence model are outstanding in performance， the flow velocity range is from 3. 14 to 3. 51m/s， in this area， simulation results of vortex field used by DES turbulence model are better than those of LES turbulence model，and the vorticity range is from 500 to 570s －1． As far as traction condition is concerned，the simulation results are distorted when DDES turbulence model and IDDES turbulence model are used，and the simulation results of multiscale vortices in mainstream region used by DES turbulence model are not as good as those of LES turbulence model，but it can reflect the basic movement trend of multiscale vortices along the circumferential direction． The simulation results used by LES turbulence model are in good agreement with the PIV experimental results， it is possible to embody the mutual mixing process of these multiscale vortices moving along the circumferential direction， the flow velocity range is from 1. 40 to 3. 60m/s，and the vorticity range is from 30 to 130s －1． It will provide some technical guidance for the precise simulation of hydrodynamic

coupling．