Abstract: This paper presents an experimental investigation on the effect of three parameters——nozzle pressure,twisted surface angle and the distance between the needle and the hollow spindle inlet on the tenacity of polyester MVS yarn.The research results show that with the increase of the nozzle pressure,the yarn tenacity first increases and then decreases.The optimal tenacity can be obtained at 500 kPa.With the increase of the twisted surface angle,the yarn tenacity first increases and then decreases.The optimal tenacity can be obtained at 60°.With the increase of the distance between the needle and the hollow spindle inlet,the yarn tenacity first increases and then decreases.The optimal tenacity can be obtained at 1.5 mm.