A packet processing method and apparatus, and a communication system are provided, and belong to the field of communication technologies. The method includes: After receiving an IPv6 packet including a first DOH, an intermediate node parses the first DOH based on a first policy, to obtain first information carried in the first DOH, and processes the IPv6 packet based on the first information. The IPv6 packet includes an RH and the first DOH is located after the RH, or the IPv6 packet does not include an RH. In this application, an intermediate node that performs parsing to obtain information carried in an IPv6 extension header may be flexibly specified, to resolve a problem that a parsing rule of an extension header of an existing IPv6 packet is not flexible enough. This application is used for packet processing.