Methods for coding a block of video data using palette coding in a video coding are disclosed. According to one embodiment, the palette transpose flag is signaled conditionally depending on the maximum index value or the palette size. If the maximum index value or the palette size is equal to or greater than a threshold size, the palette transpose flag is signaled at an encoder side or parsed at a decoder side. Otherwise, the palette transpose flag is not signaled or parsed. In another embodiment, the last palette and the last palette size are updated by the current palette with the current palette size conditionally. For example, updating the last palette and the last palette size by the current palette with the current palette size is skipped if the current coding unit is coded using a pulse-coded modulation (PCM) mode or the current palette size is zero.