The present invention disclosed a method to trace porcine DNA in a catgut suture by extracting the DNA from the catgut suture and analyzing the extracted DNA. The method of tracing porcine DNA in a catgut suture comprising steps of: homogenizing the catgut suture into a mixture of plant tissue lysis buffer and proteinase K; separating the DNA from the homogenous solution by using the column; and analyzing the extracted DNA by using polymerase chain reaction, PCR.