During synthesis of vinyl chloride by the calcium carbide-acetylene method,calcium carbide reacts with water to generate acetylene,purified acetylene is mixed with hydrogen chloride,then they react in the converter tube with mercuric chloride and activated carbon as catalysts.In this paper,structure of the converter tube was improved,fluid-flow state was changed,which reduced center temperature in the tube to improve the catalyst life and production capacity of a single converter.Currently in China,the improved converter should be widely applied in manufacturers which product vinyl chloride by the calcium carbide-acetylene method.