A transmission method and a communication apparatus provide a source access network device receives first data and a first identifier. The first identifier indicates a last data packet of the first data, and the first data is data in a first periodicity of a periodic service. The source access network device sends a handover command to a terminal device in a first time period. A start moment of the first time period is a moment at which the last data packet is sent, an end moment of the first time period is an end moment of the first periodicity, and the handover command instructs the terminal device to perform a handover to a target access network device. This avoids interruption of sending the first data by the source access network device due to the handover and improves transmission reliability of the periodic service.