The paper reviews the state-of-art for micro optical fluidic systems (MOFS), or optofluidics, which employs optics and fluidics in a microsystem environment to perform novel functionalities and in-depth analysis in the biophysical area. Various topics, which include the introduction of MOFS in biomedical engineering, the implementation of near-field optics and also the applications of MOFS to biophysical studies, are discussed. Different optical detection techniques, such as evanescent wave, surface plasmon resonance, surface enhanced Raman scattering, resonators and transistors, have been studied extensively and integrated into MOFS. In addition, MOFS also provides a platform for various studies of cell biophysics, such as cell mass determination and cell Young's modulus measurement.