Disclosed are a data transmission method, a system and an apparatus, which are used to meet transmission quality requirements of data on multiple kinds of logic channels in the event that multiple kinds of logic channels related to multimedia broadcast multicast service (MBMS) are mapped to the same transmission channel. The data transmission method provided by the present invention includes that: a network side determines multiple kinds of modulation and coding schemes (MCSs) needed to be adopted when multiple kinds of logic channels are mapped to the same transmission channel, and notifies a terminal of correspondence between logic channels and MCSs; using MCSs needed to be adopted, the network side performs modulation and coding for the data on logic channels mapped to the transmission channel, then transmits it to the terminal through the transmission channel.