Abstract: At present, conventional algorithms can′t effectively solve the inverse scattering imaging problem of electrically large objects. A hybrid imaging method based on linear sampling method (LSM) and contrast source inversion (CSI) is proposed. First, LSM truncation threshold is used to determine the object region, and a fixed value of contrast is assigned to the object region. Then, CSI iteration is carried out with this result instead of back propagation solution as the initial value to reconstruct the contrast distribution. Genetic algorithm is used to optimize the truncation threshold and the fixed contrast value, and the best choice of these two parameters is obtained. The simulation results show that the method can achieve accurately reconstruction for the electrically large object, and can get better results than the back propagation solution when there is noise.