Many proteolytic enzymes have a serine esidue as a catalytic functional amino acid. These enzymes are called serine protease and they are of extremely widespread occurrence from mammals to microbials. Also they have similar function, similar active site, similar amino acids, and similar three-dimensional structure. Therefore they have been considered in terms of evolutionary relationship. Eleven trypsins which selected by computer program FASTP were aligned by computer program VAlign. 44 amino acids were conserved and these amino acids were distributed at active site region, C-terminal $\alpha$ -helices region, and disulfide bridge region. These regions were important to perform proteolytic activity. Also, as a consequence of parise homology from VAlign, the evolutionary tree was inferred.. The bovine pancreatic trypsinogen cDNA have cloned to elucidate the evolutionary elationshp of serine proteases. Lambda gt 11 library was plated and screened with anti-trypsin antibody. The one positive clone (lambda gt T) was found and the phage DNA from this clone was prepared and then digested with EcoRI. The insert have about 0.9 kb size.