Spider silk has attracted great interest in recent years due to its superior mechanical properties for biomedical, military and other potential applications. However, due to the inability of post-expression fiber formation systems to generate spider silk proteins fibers with native properties, a new approach is being developed by replacing the silkworm silk genes with synthetic spider silk DNA. The CRISPR (clustered regularly interspaced short palindromic repeats)/cas9 system, is a new technique developed in the past couple of years. It is being utilized for gene-specific modification in this study, to allow more accurate and precise integration and replacement of the silkworm silk gene with a synthetic spider silk gene. In this study, CRISPR/cas9 system, a recently developed gene editing tool, has been applied to construct the part of transgenic silkworms for spider silk production. The technique has shown its efficiency in gene editing through NHEJ and HR in silkworm in vitro and in vivo. With this success, we are making a new generation of silkworms with spider silk in their cocoons