Embodiments of the present application provide a method for demodulating a shared reference signal, a terminal device, and a network device. The method comprises: a terminal device receives first indication information sent by a network device, the first indication information being used for indicating resource information of a target resource group allocated for the terminal device; and the terminal device determines the length of the sequence of a shared reference signal according to the resource information of the target resource group, wherein the shared reference signal is a reference signal shared by multiple terminal devices, and the length of the sequence of the shared reference signal is used for demodulating the shared reference signal. Embodiments of the present application can implement channel estimation or channel measurement.