Liquid entrainment in high-gravity (HIGEE) devices exists and reduces the separation efficiency. The flooding in HIGEE devices, called HIGEE flooding, sets an upper limit of allowable throughputs, and different flooding criteria were proposed by researchers. Using an airwater system, the experiments of liquid entrainment and HIGEE flooding were carried out in a rotating zigzag bed (RZB), as a new HIGEE device. The RZB rotor had an inner diameter of 0.101 m, an outer diameter of 0.284 m, and a height of 0.051 m. The distillation experiment was conducted in the same RZB to investigate the effect of liquid entrainment on the separation efficiency. The results show that liquid entrainment in RZB contains liquid-droplet and liquid-film entrainment. Liquid-film entrainment is far higher than liquid-droplet entrainment. Also, excessive liquid-film entrainment at the outer edge of the RZB rotor severely lowered the separation efficiency. The point at which the pressure drop increases sharply with increasing superficial liquid velocity was the first to be taken as a new HIGEE flooding criterion. The new HIGEE flooding criterion reflected the real flooding in RZB, and the previous criteria could not reflect it. The new HIGEE flooding criterion can also be applied in rotating packed beds.