This disclosure provides a packet detection method, an electronic device, a system, and a computer-readable storage medium, and relates to the field of communication security technologies. In an embodiment, detection marking information that indicates a risk in a service packet is set in the service packet. In a process of forwarding the service packet on a forwarding path, a security device forwards the service packet that carries the detection marking information, or before forwarding the service packet, the security device updates a value of a field in the service packet based on a detection result after performing security detection on the service packet. The network device sends flow security status information to a network management analysis device based on the detection marking information carried in the service packet, to assist a control plane in identifying a service flow forwarding path on which a risk exists.