The notion of joint spectrum in polarizational and spatial domains is proposed for the first time, which can depict the EM signal completely. Based on the polarization sensitive array, the joint spectrum is defined and its analytic function is presented by using MUSIC method. The estimation accuracy and resolving power are investigated to measure the performance of joint spectrum. The Cramer-Rao Bound (CRB) is used to evaluate the accuracy of the estimated direction of the arrival and polarization angle. The ambiguity function and ambiguity area are used to evaluate the resolving power in polarizational and spatial domains. The simulations verify the superiority of the joint spectrum and coincide with the theoretical analysis.