Abstract: In order to solve the problem of the upper bound of the anti-interference number of polarization sensitive array, the upper bound of the anti-interference number is formulated to the maximum number of the linearly independent steering vectors. From the perspective of Khatri-Rao product, the deterministic and general conditions for the linear independence of the steering vector are given. For the N-element dipole uniform linear arrays, it is proved that the sufficient and necessary condition for the steering vectors to be linear independent is the number of signals K<=N. When no more than two signals have the same incidence angles, it is proved that the sufficient and necessary condition for the steering vectors to be linear independent with probability 1 is the number of signals K<=2N. The results show that when the number of completely polarized main-lobe interferences does not exceed 1, the polarization sensitive array can suppress at most 2N-1 interferences. When there are 2 completely polarized main-lobe interferences or 1 partially polarized main-lobe interferences, polarization sensitive array fails to completely suppress interferences. Finally, the correctness of the theoretical result is verified by simulation, which can provide theoretical guidance for the application of polarization sensitive arrays in radar, communication, navigation and electronic countermeasures.