This standard specifies the method for determining the chlorine consumption of pulp using chemical titration to evaluate its degree of delignification. The core principle of this method is: in a strongly acidic medium, the pulp is allowed to react with a quantitative hypochlorite solution for a specified time, and then the residual chlorine is measured by indirect iodometry, from which the consumed chlorine is calculated. The chlorine consumption exhibits a linear relationship with the residual lignin content in the pulp, making it a key indicator for assessing the bleaching performance of pulp. For this test, a specialized chlorine consumption tester is required, which mainly consists of a thick-walled conical flask and a cylindrical separatory funnel. The entire determination process must also be carried out with the assistance of auxiliary equipment such as a constant temperature water bath, a magnetic stirrer, a vacuum pump (or water aspirator), and a stopwatch.