The biosensors based on biocatalytic and immunosensors have gained increasing applications in environmental biomonitoring. Along with the advances in molecular biology and biotechnology, the DNA biosensors, based on DNA interaction and using nucleic acid as recognition element, was developed. They can be used for the hybridization detection of nucleic acid sequences from infectious microorganisms, for monitoring of priority pollutants and for the interacting study of pollutants and DNA. They possess a great potential for environmental monitoring. The principle of nucleic acid hybridization biosensors and their applications for the detection of environmental microorganisms and the priority pollutants was briefly described.