The embodiments of the disclosure relate a method for determining a state of a terminal device, a terminal device and an access network device. The method includes that: a terminal device receives configuration information from an access network device, the configuration information being configured to instruct the terminal device to enter an inactive state; and the terminal device determines whether to enter a power saving mode under the inactive state, a radio frequency module of the terminal device in the power saving mode being off. According to the method for determining a state of a terminal device, terminal device and access network device of the embodiments of the disclosure, the terminal device under the inactive state may enter the power saving mode, and power consumption of the terminal device is further reduced.