Embodiments of the present invention disclose a method and an apparatus for transmitting data, and the method includes: first setting at least two second resource groups in each first resource group of at least one first resource group, and setting at least two reference signals in each of the second resource groups; then encoding data to be transmitted and generating two data streams from the encoded data; then, mapping the two data streams onto an available resource element of two different antenna ports, in which the reference signals corresponding to the two different antenna ports are set on two different second resource groups; and finally, transmitting, on the available resource element of the two different antenna ports, data on the two antenna ports. The present invention is applicable to the field of communications systems.