The present invention relates to the technical field of mobile communications. Embodiments of the present invention provide a data transmission method and device in an unlicensed frequency band. The method comprises: determining a termination position of to-be-transmitted data in a radio frame in an unlicensed frequency band; determining position indication information according to the termination position; and sending the position indication information, so that a user equipment determines, according to the position indication information, the termination position of the to-be-transmitted data in the radio frame in the unlicensed frequency band. In the method provided by the embodiments of the present invention, a termination position of transmitted data in a radio frame in an unlicensed frequency band is indicated to a user equipment by using position indication information, so that the user equipment is enabled to determine, according to the position indication information, the termination position of the transmitted data in the radio frame, and therefore accurately receives the data according to the termination position and the receiving position of the transmitted data.