The invention provides a halamine antibacterial agent and a synthetic method and application thereof. The halamine antibacterial agent is a compound with a structure which is shown as a formula (I) or a formula (II). The synthetic method comprises the following steps of: reacting by taking epoxy chloropropane and cyanuric acid or a derivative of the cyanuric acid as synthetic raw materials at the temperature of between 5 and 50 DEG C for 6 to 12 hours, filtering, removing impurities to obtain a halamine antibacterial agent precursor with a structure which is shown as a formula (III) or a formula (IV), and performing halogenating reaction to obtain a finished product of the halamine antibacterial agent. According to the application of the halamine antibacterial agent to the preparation of an antibacterial material, the antibacterial material is prepared by the following steps of: treating a material to be treated by a working solution prepared from the halamine antibacterial agent precursor, taking the material out, drying, treating at the temperature of between 80 and 200 DEG C for 3 to 60 minutes, and performing halogenating reaction. According to the method, reaction condition is mild, a process is simple, and raw materials are low in cost and readily available; and the halamine antibacterial agent synthesized by the method and the halamine antibacterial agent precursor are water-soluble, high in yield, safe and non-toxic, and can be prepared into antibacterial textiles with high antibacterial performance.