Security policy is one of the core functions of NGAF. It can detect the traffic passing through NGAF safely, block malicious behaviors, and perform the correlated blocks. A closed-loop mechanism is established through prediction before an event, safety protection during the event, detection, and response after the event. Security policies mainly include web application firewall, intrusion protection, content security, tamper protection, botnet detection, DDoS protection, service model learning and supervision, server access authentication, and risk analysis.