This paper presents a new self-interference cancellation mechanism via cooperation of the source and relay node in Full-Duplex Decode-and-Forward relay system. According to previous research of full-duplex relay system, we find that most of the cancellation methods are focused on the receive chain which is complex and still left with residual-interference. Thus it causes degradation of performance due to high decoding error probability. In order to improve this situation, we design the pre-aliasing method. It is based on channel-state-information which is estimated after partial self-interference cancellation. Results show that this method is flexible in realization and can enhance the system reliability.