Low bit-rate image coding is essential for many visual communication applications. The block-based discrete cosine transform coding has been widely adopted in image or video compression. However, the coding produces blocking artifacts that severely degrade the perceptual quality of the images or videos. In this paper, an L-filter combining a genetic algorithm (GA) for reducing the blocking artifacts in compressed images is proposed. The L-filter is used for reducing the block artifacts and the GA is used to search the proper parameters for the L-filter. The proposed approach has the advantage of combining the powerful enhancement of the L-filter and the global solution exploration of the GA. In experiments, compressed images are processed by the proposed approach and other methods for comparison. The experimental results reveal that the proposed approach provides a simple but effective way to produce the best result based on the visual inspection and the PSNR objective criterion.