The invention relates to a method for treating received and transmitted joint signals in a multi-user multi-aerial system, a key station obtains the estimated value of present communication channel information and noise variance, the method comprises: firstly, breaking up a communication channel matrix in block diagonal, obtaining a unitary matrix with block diagonal characteristics and an expanded communication channel matrix after transformation, respectively acting each block of the unitary matrix on each corresponding user side to balance the communication channel partly, balancing the expanded communication channel matrix after the transformation on a key station end, wherein the key station end utilizes a lattice-reduction technique to obtain reduction bases with better performance, and then utilizing the reduction base to process by interference elimination to achieve the purpose for jointing a receiving end and a transmitting end to eliminate interference between multi-users and between multi-aerials. The invention increases the performance of an existing simple base on the basis of a scheme of a block diagonal decomposition method, increases diversity gain, simultaneously, keeps the increased lattice-reduction treatments with polynomial complexity still, and thereby achieves the purpose for increasing the system performance and the capacitance significantly with lower complexity.