A good retention and filtering aid is a prerequisite and necessary factor to ensure smooth operation of the paper machine and good paper quality. Medium molecular weight cationic polyacrylamide is one of the most commonly used retention aids in paper-making. The use of cationic polyacrylamide can reduce fiber and filler loss and thus reduce costs, as well as reduce the consistency and ash content of the pulp, extend the life of the forming fabric, and improve the smoothness and opacity of the paper. In many field conditions, cationic polyacrylamide alone can be used to achieve retention and filtration aid effects.