This article deals with the characteristics of weakly swirling turbulent flow field in a Turbid Water Hydraulic Separation Device (TWHSD) through experimental and numerical researches. The flow field was measured by PIV, which provided streamlines, vortex structure, vorticity and velocity distribution in different test planes in the TWHSD. On the basis of the experimental results, the tangential and radial velocity distributions of the swirling flow field were obtained. Meanwhile, the numerical simulations were conducted with the RNG and RSM turbulence models, respectively. According to the experimental and numerical results, the characteristics of the clear water flow field inside the TWHSD were determined. In view of simulation accuracy and time consumption, it is suggested to apply the RNG model instead of the RSM model, which is more time consuming, to make further study on two-phases flow fields in the device.