Disclosed in the present application are a data transmission method and apparatus and a computer storage medium, to map a data layer to a DMRS port used in transmission according to a preset DMRS port ordering rule, and perform transmission. The data transmission method provided in an embodiment of the present application comprises: determining a preset demodulation reference signal (DMRS) port ordering rule; and mapping a data layer to a DMRS port used in transmission according to the preset DMRS port ordering rule, and sending the data layer to a terminal.