Anhydrous hydrogen fluoride contains trace amounts of water.According to the national standard GB/T 7746-2011《Industrial Anhydrous Hydrogen Fluoride》,the water content in class I products is required to be less than 50 x 10-6,and the precision is higher.In the production process,there are very strict requirements for the control of water content in anhydrous hydrogen fluoride,because the fluctuation of the water content of anhydrous hydrogen fluoride will affect the quality of the product and aggravate the corrosion of the equipment,so it is necessary to measure the water content of anhydrous hydrogen fluoride in a timely and stable manner to facilitate the production control.The detection method of water content has already given in the national standard GB/T 7746-2011《Industrial Anhydrous Hydrogen Fluoride》.And on that basis,after analyzing and comparing the experiments,optimize and improve analytical and testing methods,the water content of anhydrous hydrogen fluoride was detected online.This method can makes accurate detection data,concurrently,this method is uncomplicated and safely.