This application relates to the field of wireless communications technologies, and in particular, to a terminal device, an access network device, an air interface configuration method, and a wireless communications system, so as to establish a connection between a terminal device and two radio access network devices. A second access network device in a radio access network determines air interface configuration information of an air interface between a terminal device and the radio access network, and sends a first air interface configuration message comprising the air interface configuration information to a first access network device in the radio access network, where the first access network device and the second access network device use different wireless communications standards.