In this paper, we study the hierarchical structure of a chaotic sea and the existence condition and delimitation method of island chain for Lozi map. The regular island chains associated with elliptic periodic points in chaotic sea are investigated by the theory presented in [15]. A method for determining the boundaries of the island chain is introduced. Multiple layers of a chaotic sea are found which are dependent on initial values. A method of determining the layer boundary of chaotic sea is presented. We found that critical line plays an important role in determining the boundaries of the layer of chaotic sea. We also prove that all trajectories are symmetric with respect to the diagonal dividing line of the second and fourth quadrants.