This application discloses a NB-IoT-based communication method and an apparatus, to evolve a NB-IoT communication technology into an NTN. The method is as follows: A terminal device generates an uplink signal, including a superframe which includes a synchronization sequence located in first duration of the superframe and a data frame located in second duration which is after the first duration, the synchronization sequence successively includes a first sequence repeated Ni times and a second sequence repeated N2 times, the second sequence is obtained by multiplying the first sequence by −1, a part of consecutive sequences of the synchronization sequence are used as a first synchronization reference sequence that is obtained based on the second sequence repeated N2 times and one or more first sequences that are sorted from back to front in the first sequence repeated N1 times. The terminal device sends the uplink signal to a network device.