A method and apparatus use an Inter coding tool and OBMC (Overlapped Block Motion Compensation). According to one implementation, a method of video coding using OBMC (Overlapped Block Motion Compensation) operates by receiving input data associated with a current block, wherein the input data correspond to pixel data to be coded at an encoder side or coded data to be decoded at a decoder side, applying the OBMC to the current block depending on one or more constraints, and signaling an OBMC syntax conditionally at the encoder side or parsing the OBMC syntax conditionally at the decoder side for the current block, wherein the OBMC syntax indicates whether the OBMC is applied to the current block.