Embodiments of the present invention relate to the field of communications, and provide a method and a device for transmitting data by using a multidimensional constellation diagram, which can further improve bit error rate-signal to noise ratio performance by means of a multidimensional constellation diagram. The method is: First, bit data is mapped, by using an n-dimensional constellation diagram, into a column vector including n real numbers, then the n real numbers included in the column vector are modulated by using a resource element and sent, and after demodulating the n real numbers from a received signal, a receiving device finds, in the n-dimensional constellation diagram, a constellation point with coordinate values having a closest Euclidean distance to a point with coordinates being the n real numbers, and finally maps the coordinate values of the constellation point back into the bit data.
