A beamforming model of multi-beam direct-radiating array antenna is established.A modified complex-coded genetic algorithm is introduced.This genetic algorithm chooses different mating operator in different period of time.It selects different crossover operator such as extrapolation

interpolation

and orthogonal direction extrapolation and interpolation crossover operator in different generation.This algorithm overcomes the disadvantages of existing genetic algorithms — prematurity and the dependence of convergence on the initial population

and enhances global convergence performance of the algorithm.It uses "remember operator" to suppresses the DOA-hop jamming.Computer simulation shows that this method has the advantages of high resolution and reliability in LEO satellite beam-space adaptive nulling.Its anti-jamming ability is better than the traditional adaptive beamforming algorithms.