Abstract: The interference alignment (IA) problem of multiple-input multiple-output (MIMO) interference channels with asymmetric structure was studied. The interference alignment problem of the whole system was resolved into the IA problems of two subsystems to build the equations which could be solved by symbolic computation software using the interaction between the subsystems. The proposed method can realize the IA of an asymmetrical MIMO channel under the condition that the number of antennas is minimum. Taking 4-user as an example to show the process of the proposed solution, simulation result reveals the advantages and disadvantages of the method which validates the proposed method and analyzes the complexity.