Cationic antimicrobial polymers, as a kind of novel antimicrobial material with unique antimicrobial mechanism and high antimicrobial activity, can effectively solve the problem of bacterial resistance, which have caused widespread concern. Although cationic antimicrobial polymers have potent antimicrobial activities, the factors that affect their antimicrobial activities, including the balance of hydrophilicity and hydrophobicity, molecular weight, alkyl chain length, counter ions, and so on, are reviewed. Antimicrobial activity is one of the important factors to evaluate the pros and cons of antimicrobial agents. Thus, it is of great significance for optimizing or developing the safer and more efficient cationic antimicrobial polymers by controlling the factors affecting antimicrobial activity. In this review, multiple antimicrobial strategies of different modes acting on bacteria are firstly summarized. Then, the research progress of natural cationic antibacterial polymers, quaternary ammonium salt polymers, N-halamine polymers, phosphonium and sulfonium salt polymers, guanidine salt polymers and antibacterial hydrogels are listed based on the parameters affecting the properties of cationic antimicrobial polymers. In addition, the antibacterial coatings, membranes or gels fabricated with some cationic antimicrobial are also described. Finally, the current challenges about realizing the clinical application of antibacterial agents and the future perspectives in this field are discussed.