Abstract: Inertial microfluidic chips have been widely used in the fields of particle or cell focusing, capturing and sorting. Among many curved channels, zigzag channel can reduce the number of particle equilibrium positions and was easy to integrate, which was a very promising particle manipulation structure. Numerical simulations were conducted to study the effect of sawtooth structure parameters on particle inertial focusing. The smaller the sawtooth angle was, the stronger the secondary flow will be, and the better focusing performance will be achieved, but the pressure drop should be integrated. The ratio of height to width (H/W) affects focusing mode: in the channel of H/W＜1, particles are focused in the width direction; in the channel of H/W～0.5 particle focusing tends to single focusing mode. The results were of guiding significance for the selection and optimization of zigzag channel structure in microfluidic chips.