Objective To compare the efficacies of three methods (Qiagen kit, Tiangen kit and modified manual extraction) for extracting human genomic DNA from fresh and frozen blood samples. Methods Twenty samples of intravenous whole blood (5 mL/sample) were collected from pancreatic cancer patients and centrifuged. Each sample was then divided into fresh and frozen samples. Human genomic DNA was extracted from the fresh blood samples within 12 h by the three methods: Qiagen kit, Tiangen kit and modified manual extraction. The frozen sample was thawed to room temperature after preserved at -40℃ for 72 h and the DNA was extracted by the same three methods. The integrity of the DNA products was examined by agarose gel electrophoresis; the purity and concentration were examined by nucleic acid protein detector; and the cost and time spent of the 3 methods were evaluated. Results The DNA integrity by the modified manual method was better than those of the other two methods using kits. As for purity, some frozen samples presented ghost peaks of contamination. As for the yield of the DNA products, the Qiagen kit was superior to Tiangen kit for both fresh and frozen samples. The yield of modified manual method was similar to that of Tiangen kit for frozen samples, and was the lowest one for fresh samples. Methods using kit took less time but cost more. Conclusion The modified manual extraction can obtain longer and more intact genomic DNA compared with the other two methods. Although the modified manual extraction is inferior in yield and time saving, it costs less and is more suitable for genomic DNA extraction from large frozen samples.