Abstract: Liquid channelling,a special nonuniform flow phenomenon on distillation plate,is studied.The hot-film anemometer is used to measure the liquid channelling flow rate on a φ1200 hing-turndown-ratio valve plate for the first time.The Plate is divided into two rregions,the bubbling region with mass transfer and the channelling region,and the difference equations of material balance in each region are solved to give the relationships between liquid channelling and plate efficiency under various operating conditions.The results can be utilized to determine the liquid channelling effect on industrial distillation.