The ball valve made of glass fiber reinforced plastic(GFRP) has the advantages of high strength,low density,acid and alkali corrosion resistance,etc.It has gradually replaced the metal ball valve to apply in the chlor-alkali chemical pipeline.Taking DN50 GFRP floating ball valve as the research object,the influence of plug preload,friction coefficient of sealing parts and sealing surface width on the sealing performance under atmospheric pressure was analyzed,and the order of the influence of recommended working pressure of valve ball and overall design parameters of GFRP floating ball valve on sealing performance was explored.The results show that the maximum working pressure of GFRP floating ball valve shall not exceed 3 MPa.Under atmospheric pressure environment,more than 550 N plug preload is required to ensure the normal sealing of the ball valve.Increasing the friction coefficient of the sealing surface can improve its sealing performance.When the friction coefficient of sealing surface reaches 0.2,the minimum sealing specific pressure on the sealing surface is closest to the critical sealing specific pressure,and the material utilization rate is the highest.With the increase of sealing surface width,the maximum sealing pressure decreases first and then increases.Considering the service life of ball valve and material utilization rate,the optimal sealing surface width of the valve seat is 8.65 mm.The sealing surface width has the greatest influence on the sealing performance of GFRP floating ball valve,followed by the cock plug preload,and the friction coefficient has the least influence.