We propose a robust phase unwrapping method to coregistration error for multibaseline InSAR systems.In the method

the optimal joint data vector is determined by the direction of the coregistration

the true steering vector with large coregistration error is computed according to the data vector

and then the beamforming technique with the steering vector is used to unwrapping the InSAR interferometric phase.The method can carry out image coregistration

interferometric phase noise filtering and phase unwrapping simultaneously.Computer simulation results show that the method can provide accurate estimate of the absolutely interferometric phase even when the coregistration error reaches one pixel.