Most recent researches have concentrated on the rapid development of enzymesensors, immunosensors and microbial biosensors, whereas the studies about the DNA biosensor are relatively scarce. The principles of DNA sensor based on the principle of nucleic acid hybridization are reviewed. Several kinds of DNA sensors such as electrochemical, optical, acoustic and piezoelectric are introduced and compared, the high specificity and low responsibility of DNA sensor are also discussed. Generally speaking, DNA biosensor has a more prospective future.