Abstract: Experiments of liquid-solid two-phase flow in a tube with a spiral insert were carried out to research the distribution of vorticity field and velocity field using particle image velocimetry (PIV) for exploring the influence of spiral insert and liquid-solid two-phase flow on the flow field. The experimental results show that the liquid-solid two-phase spiral flow was formed and the motion intensity of fluid was increased under the action of spiral insert. In the range of Re=26 400-33 000, the total average vorticity was raised by 21.4%-35.8% over plain tube; the average radial velocity was 6.5-19.8 times of that of the plain tube; the radial velocity fluctuated in positive and negative directions and its fluctuation was 51-609 times of that of the plain tube. The axial velocity increased from the wall to the center of the tube, and its fluctuation and the average turbulent energy were increased by 41.5%-60.6% and 162.7%-254.6% over the plain tube respectively. Therefore, liquid-solid two-phase spiral flow is more conducive to heat transfer.