A pilot sequence transmission method, comprising: determining a first pilot sequence used to indicate whether a terminal device is in an active state; determining a second pilot sequence, corresponding to the first pilot sequence, used for uplink data demodulation; mapping the first pilot sequence to a first orthogonal frequency division multiplexing, OFDM, symbol of a grant free transmission resource; mapping the second pilot sequence to a second OFDM symbol of the grant free transmission resource; and sending the first pilot sequence and the second pilot sequence by using the first OFDM symbol and the second OFDM symbol; wherein the mapping the first pilot sequence to a first orthogonal frequency division multiplexing, OFDM, symbol of a grant free transmission resource comprises: mapping the first pilot sequence to a part of a subband of the first OFDM symbol of the grant free transmission resource; wherein mapping the first pilot sequence to a first orthogonal frequency division multiplexing, OFDM, symbol of a grant free transmission resource comprises: mapping the non-zero element comprised in the first pilot sequence to a first subband of the first OFDM symbol of the grant free transmission resource, wherein the first subband comprises M resource elements REs, a non-zero symbol formed after the non-zero element is mapped is an M-order Walsh code, and M is a positive integer and is an exponential power of 2. determining a first pilot sequence used to indicate whether a terminal device is in an active state; determining a second pilot sequence, corresponding to the first pilot sequence, used for uplink data demodulation; mapping the first pilot sequence to a first orthogonal frequency division multiplexing, OFDM, symbol of a grant free transmission resource; mapping the second pilot sequence to a second OFDM symbol of the grant free transmission resource; and sending the first pilot sequence and the second pilot sequence by using the first OFDM symbol and the second OFDM symbol; wherein the mapping the first pilot sequence to a first orthogonal frequency division multiplexing, OFDM, symbol of a grant free transmission resource comprises: mapping the first pilot sequence to a part of a subband of the first OFDM symbol of the grant free transmission resource; wherein mapping the first pilot sequence to a first orthogonal frequency division multiplexing, OFDM, symbol of a grant free transmission resource comprises: mapping the non-zero element comprised in the first pilot sequence to a first subband of the first OFDM symbol of the grant free transmission resource, wherein the first subband comprises M resource elements REs, a non-zero symbol formed after the non-zero element is mapped is an M-order Walsh code, and M is a positive integer and is an exponential power of 2. mapping the first pilot sequence to a part of a subband of the first OFDM symbol of the grant free transmission resource; wherein mapping the first pilot sequence to a first orthogonal frequency division multiplexing, OFDM, symbol of a grant free transmission resource comprises: mapping the non-zero element comprised in the first pilot sequence to a first subband of the first OFDM symbol of the grant free transmission resource, wherein the first subband comprises M resource elements REs, a non-zero symbol formed after the non-zero element is mapped is an M-order Walsh code, and M is a positive integer and is an exponential power of 2.