Qualitative and quantitative filter paper can be classified into two types. In the application of analytical chemistry, when after filtered to separate the sediment inorganic compounds, collect in the residue on the filter paper, can be used to calculate the turnover rate in the experimental process. Qualitative filter paper after filter has more cotton fibers, and therefore applies only to qualitatively; filter paper, especially for gray-level filter through a special treatment program, and can effectively resist chemical reactions, so fewer impurities generated, can be used for quantitative analysis. In addition to General laboratory filter paper, lives and works on paper a lot of applications. Is a widely used paper coffee filter paper, tea bag outer filter provides high flexibility and high wet strength characteristics. Other air filter paper using the suspended particles in the air, and fiber filter paper in different industrial applications.