In this paper, the research progresses concerning the biocidal performance and mechanism of polydimethyldiallylammonium chloride (PDMDAAC) were reviewed based on the literatures. The discussion about the biocidal performance of PDMDAAC was carried out in four aspects, such as applied fields, action objects, action modes and action effects. The information about the biocidal mechanism of PDMDAAC was summarized. Therefore, it was pointed out that the present recognition about the biocidal performance of PDMDAAC was not satisfactory, and the description about the biocidal mechanism of PDMDAAC had almost not been touched. Finally, a series of valuable suggestions were put forward for further researches on the biocidal performance and mechanism of PDMDAAC.