A method of signaling of coding modes including an IntraBC mode (Intra-block copy mode) to improve the coding efficiency is disclosed. In one embodiment, the partition mode associated with IntraBC mode and the corresponding partition mode for Inter mode use the same binarization process and the same context modelling. In another embodiment, the displacement vector of IntraBC prediction for the chroma block is derived from the displacement vectors of the corresponding luma block. In yet another embodiment, a non-square PU is partitioned into multiple TUs (transform units) and IntraBC prediction is performed TU by TU.