The invention provides a precoding method based on interference alignment, which comprises the steps of calculating decoding matrixes of a plurality of cells by using channel state information between a receiver and a base station, acquiring and calculating a precoding matrix of a transmitter according to up channel state information of the cell where the receiver is located, and a decoding matrix of the cell where the receiver is located, and precoding down data according to the precoding matrix of the transmitter. The method obtains the decoding matrixes of the cells, calculates the precoding matrix of the transmitter according to the decoding matrixes of the cells and precodes the down data according to the precoding matrix, so that the interactive quantity of channel information and the antenna quantity of a client are effectively reduced, and the system complexity is reduced.