The principle of surface plasmon resonance and the applications of this theory,particularly in biological fields are reviewed.Using this technique,the experimental system can be directly probed and followed in real time and in situ without the requirement for additional parameters, such as labelled moleculars.With high sensitivity,the sequential reactions during adsorption or desorption can be monitored. So far, the applications are involved in biological binding analysis, kinetics, affinity measurement, immuno-distinguish, structure-actmty study and nucleic acid research, etc.