This paper proposes an adaptive video pre-processing algorithm for video coding. This algorithm works on the original image before intra- or inter-prediction. It adopts Gaussian filter to remove noise and insignificant features existing in images of video. Detection and restoration of edges are followed to restore the edges which are excessively filtered out in filtered images. Rate-Distortion Optimization (RDO) is employed to decide adaptively whether a processed block or a unprocessed block is coded into bit-streams doe more efficient coding. Our experiment results show that the algorithm achieves good coding performances on both subjective and objective aspects. In addition, the proposed pre-processing algorithm is transparent to decoder, and thus can be compliant with any video coding standards without modifying the decoder. This algorithm proposes the original image before intra- or inter-prediction. It provides Gaussian filter to remove noise and insignificant features existing in images of video. Detection and restoration of edges are followed to restore the edges which are excessively filtered out in filtered images. Rate-Distortion Optimization (RDO) is employed to decide adaptively whether a processed block or a unprocessed block is coded into bit-streams doe more efficient coding. that the algorithm achieves good codingations on both subjective and objective aspects. In addition, the proposed pre-processing algorithm is transparent to decoder, and therefore can be compliant with any video coding standards without modifying the decoder.