A network device adds an extreme low latency (ELL) service packet to an ELL queue, and adds a (time sensitive) TS service packet to a TS queue. A packet in the TS queue is sent within a time window corresponding to the TS queue, and the packet in the TS queue is not allowed to be sent within a time period beyond the time window corresponding to the TS queue. When a remaining time period obtained by subtracting a time period required by a to-be-sent TS service packet within the time window from the time window is greater than or equal to a first threshold, a packet in the ELL queue is allowed to be sent within the time window corresponding to the TS queue. The first threshold is a time period required for sending one or more ELL service packets in the ELL queue.