Abstract: Objective To solve the problems of DNA testing in trace sample. Methods Applying original carrier method to detect known trace blood DNA and to compare it with the results obtained by high effective DNA extracting method of Chelex-100. Results The carrier method not only could obtain the right STR genotype in the trace blood sample, but also was twice as sensitive as the Chelex-100 method. Conclusion The carrier method could improve the DNA detection in trace sample. It is easy to operate and is much more valuable in the forensic case analysis.

Key words: forensic genetics, extraction, carrier method, DNA examination