The present invention provides a data transmission method and apparatus. The method includes: transmitting physical downlink channel data according to a first-type reference signal (RS) or a second-type RS or a third-type RS. The method of the present invention ensures a balance between data transmission performance and RS overheads for different NarrowBand-Internet Of Things (NB-IOT) physical downlink channel data, thereby resolving the problem in the related art of not knowing which RS is to be used to transmit NB-IOT physical channel data.