Abstract: The generalized sidelobe canceller (GSC) is utilized widely in the interference suppression in the traditional airborne phased array radars. The selection of the auxiliary channels in the GSC affects the interference suppression performance directly. In a conformal array, the unit pattern response of each array element is not the same due to the different placements of array elements. Therefore, it is more significant to select the appropriate auxiliary channels for the GSC. Based on the signal model of the conformal array, this paper proposes an optimization method which aims to minimize the output of generalized sidelobe cancellation. In order to solve the non-convex 0-1 optimization problem, the paper adopts the penalty sequential convex programming (SCP) method and the majorization-minimization (MM) algorithm to solve it. The simulation and numerical results prove that the proposed algorithm can select the auxiliary channels with great interference suppression performance in the conformal array.