Provided in embodiments of the present application are a method and apparatus for determining trigger state, a terminal device, and a communication device; the method comprises: a terminal device receiving first configuration information sent by a network device, the first configuration information comprising configuration information of at least one trigger state; the terminal device receiving first control information sent by the network device, the first control information comprising a first information domain; the terminal device determining a first trigger state identifier on the basis of the value of the first information domain, and determining a corresponding first trigger state in the first configuration information on the basis of the first trigger state identifier; or, the terminal device determining a first trigger state at a target position in the first configuration information on the basis of the value of the first information domain.