This standard specifies the method for determining the base number of samples by the Titrimetric method of perchloric acid potential, including two types of positive titration and back titration, each type is divided into A method and B method. It is suitable for the determination of petroleum products, used oils and additive alkaline components, such as organic bases, inorganic bases, amine compounds, etc. The method outline includes positive titration methods and back titration methods. Different methods are selected according to the situation of the sample. Aceticacid glacial standard titration solution is used for titration, and the end point is judged by the potential leap of Potentiometric titration, poten-tiometry Linear dispersion.