The present invention relates to a data transmission method and device, a user equipment, and a base station. The data transmission method comprises: when the length of cached data of a user equipment (UE) is greater than or equal to a first preset threshold, grouping the cached data in a preset mode to obtain two groups of data; and uploading the two groups of data to a base station by means of a mobile network and a wireless local area network (WLAN), respectively. By means of the technical solution of the present invention, resources of a mobile network and a WLAN can be better integrated, thereby solving the problem in the prior art of low network utilization rate of the WLAN; moreover, the network burden during data transmission by means of the mobile network is significantly reduced, and the data transmission performance of the UE is improved.
