An information transmission method related to the field of communications technologies includes: generating an orthogonal frequency division multiplexing (OFDM) symbol, where the OFDM symbol includes a pi/2-BPSK modulated data signal and a pi/2-binary phase shift keying (BPSK) modulated phase tracking reference signal (PTRS); and sending the OFDM symbol. This method may be applied to an uplink single carrier transmission scenario or a downlink single carrier transmission scenario.