The invention discloses a data transmission method and device. The method comprises the following steps that: network equipment determines data to be transmitted in a sub-frame of a first carrier; the network equipment generates N transmission sequences according to the data to be transmitted, wherein N is the number of OFDM (Orthogonal Frequency Division Multiplexing) symbols included in the sub-frame; and the network equipment transmits Ath to Nth transmission sequences in the N transmission sequences in sequence starting from an Ath OFDM symbol to an Nth OFDM symbol in a first sub-frame, and transmits first to (A-1)th transmission sequences in the N transmission sequences in sequence starting from a first OFDM symbol to an (A-1)th OFDM symbol in a second sub-frame, wherein A is greater than or equal to 2 and smaller than or equal to N, the second sub-frame is positioned after the first sub-frame, and one transmission sequence occupies one OFDM symbol for transmission.