Severe combined immune deficiency (SCID) pig is very important research model for biomedical research, such as the development of humanized tissues and organs for transplantation and long-term evaluation of transplanted cancer or stem cell of human origin. FOXN1 gene encodes a transcription factor essential for the development and function of thymic epithelial cells (TECs), the primary lymphoid organ that supports T-cell development and selection. In this study, we are going to produce the FOXN1 KO SCID pigs using the Crispr/Cpf1 method. Porcine genomic DNA sequences were analyzed and the target sequences were selected using a web tool, Benchling (https://benchling.com/). The designed crDNA oligos was synthesized by the Oligonucleotide Synthesis Service (Macrogen Inc., Seoul, Korea). To generate the AsCpf1-mCherry-Puro construct, pTE4396 (#74041; Addgene, Cambridge, MA, USA) was modified by removing the NeoR/KanR sequence using BstBI and SmaI. Then, the mCherry-Puro sequence from pSicoR-Ef1a-mCh-Puro (#31845; Addgene, Cambridge, MA, USA) digested with the same restriction enzymes was inserted into the aforementioned NeoR/KanR-deleted vector. The crDNA #1 or crDNA #2 was inserted into the pTE4396 and AsCpf1-mCherry-Puro vectors in the U6 promoter region using BsmBI enzyme, respectively. The two vectors were transfected with lipofectamine 3000 (Life Technologies, Grand Island, NY, USA) and selected with puromycin and G-418 antibiotics. As a result, we established a cell line into which two vectors (pTE4396+crFOXN1#2 and AsCpf1- mCherry-Puro+ crFOXN1#1) and were inserted. Further studies are needed to characterize FOXN1 KO cell lines.