Embodiments of this application provide a method for obtaining path information and an apparatus, relate to the communications field, and can accurately obtain a forwarding path for detecting a service packet. A service packet is obtained, where the service packet is a target service packet or an updated target service packet, the target service packet is a service packet that matches a flow rule, and the flow rules used to obtain the service packet that matches the flow rule; an ingress interface information field and/or an egress interface information field is/are generated according to a path detection tag on an ingress interface and/or an egress interface through which the service packet passes. The method is used to obtain path information of the service packet.