A two-stage cyclone combining multiple helical tubes and a cylinder was designed to improve the separation efficiency. The liquid-solid two-phase flow characteristic and separation performance were investigated inside the cyclone by experiment and numerical simulation. The enhanced separation mechanism was revealed which the spiral tube group in parallel connection method was used as the cyclone inlets. The results showed that the first stage swirling flow was formed inside the spiral tube, and the fluid was subjected to centrifugal force based on the Dean eddy current principle. The denser solid particles moved towards the outside of the spiral tube, and the solid phase was concentrated on the outside and bottom of the spiral tube. Multiple spiral tubes were evenly arranged in the circumferential direction, and all of the spiral tube outlets were tangentially installed to the inner wall of the cyclone. The jet flow superposition was generated and the second stage swirling flow was strengthened. Three factors and five levels of the first stage swirl parameters were selected for orthogonal test, and the conclusion was obtained that the spiral tube number N had the most significant impact on the liquid-solid separation in the second stage swirling region. Under the same flow rate of a single tube, the solid bottom flow distribution rate decreased as the number of helical tubes increased. In the second stage swirling region below the spiral tube outlets, the swirling velocity and axial velocity were relatively lower for N≤3, and there were a large number of particles in the central region. In the secondary swirl region with N>4, the shear layer between adjacent jets was superimposed, and the fluid vortex near the outlet of the spiral tube was significantly increased, resulting in enhanced disturbance of axial flow to the central fluid. The appropriate number of spiral tubes effectively enhanced the swirling intensity near the inner wall, with relatively less disturbance to the central fluid. The distribution of particles in the near wall swirl zone increased, which was beneficial for the liquid-solid separation process in the two-stage swirling cyclone.