Forming nulls in the radiation pattern of an antenna is to suppress the interference from certain di- rections or to cancel desired signals. This letter presents an effective method based on the Gram-Schmidt or- thogonal algorithm for forming nulls in the subarray of a large array. The theory and realizing methods are discussed, and the corresponding formulas are derived in details. The simulation results are given to demon- strate the feasibility, the availability and the quick-convergence of the presented method. Forming nulls in the radiation pattern of an antenna is to suppress the interference from certain di- rections or to cancel the desired signals. This letter presents an effective method based on the Gram-Schmidt or-thogonal algorithm for forming nulls in the subarray of a large The theory and realizing methods are discussed, and the corresponding formulas are derived in details. The simulation results are given to demon- strate the feasibility, the availability and the quick-convergence of the presented method.