Spider silks are well known for their superior mechanical properties that are stronger and tougher than steel despite being assembled at close to ambient conditions and using water as the solvent. However, it is a significant challenge to utilize spider silks for practical applications due to their limited sources. Fortunately, genetic engineering techniques offer a promising approach to produce useable amounts of spider silk variants. Starting from these recombinant spider silk proteins, a series of experiments and simulations strategies are developed to improve the recombinant spider silk proteins (RSSP) material design and fabrication with the aim of biomimicking the structure-property-function relationships of spider silks. Accordingly, in this review, the authors first introduce the structure-property-function relationship of spider silks. Then, the recent progress in the genetic synthesis of RSSPs is discussed and their related multiscale self-assembly behaviors is summarized. Finally, the authors outline works utilizing multiscale modeling to assist RSSP material design.