The present invention relates to the communications field, and discloses a data transmission method, a device, and a system, so as to resolve a problem in the prior art that user equipment cannot correctly parse data or measure a channel due to incapability of identifying different operators. A specific solution is: obtaining a scrambling code sequence, where the scrambling code sequence is generated according to a specific sequence of an operator to which a first device belongs; scrambling data according to the scrambling code sequence to obtain the scrambled data; and sending the scrambled data. The present invention is used for data transmission.