Due to overlapping frequency bands between frequency-consuming devices, the local transmitter will cause serious collocation interference to the receiver, causing the saturation of receiver antenna interface and failing to work normally. In response to the above problems, a collocation interference suppression method based on auxiliary array was proposed, a collocation interference suppression system model based on auxiliary array was established, the expression of minimum residual interference power was derived, channel conditions that need to be satisfied for collocation interference suppression was proposed. In addition, the location of the auxiliary was analyzed when main-transmitter array was non-cooperative, and the relationship of the locations of arrays was analyzed when the main-transmitter array was cooperative. The theory and simulation results show that the collocation interference suppression method based on auxiliary array can effectively suppress collocation interference at the receiver antenna interface without affecting the transmission efficiency of the local main-transmitter array.