Chloroacetone reacts with chlorine in a tubular reactor, and the length and diameter of the reaction tube directly affect the result of the reaction. It has been reported in the U.S. patent that acetone reacts with chlorine in a glass tube with a diameter of 1mm and a length of 10mm to synthesize a Chloroacetone, the reaction selectivity is very high, but the reaction tube of this size is obviously not of practical application value. From the practical application, we have observed the length of the reaction tube in a wide range and the influence of the reaction tube diameter on the reaction result Generally, the length of the reaction tube increases, the residence time of the substance in the reaction tube increases, and the reaction conversion rate increases, but at the same time the content of dichloroacetone also increases, and the reaction selectivity decreases. The diameter of the reaction tube increases, and the materials are mixed in the reaction tube. Intensified, the reaction selectivity will also decrease, and the diameter of the reaction tube decreases, the reaction conversion rate decreases. Comprehensively consider the impact of the length and diameter of the reaction tube on the reaction results to determine the appropriate reactor size. The reaction results under different tube lengths are listed.