The applications and development of optical gas cells in tunable diode laser absorption spectroscopy (TDLAS) are overviewed. The structures and principles of several types of absorption cells including the While, Herriott, matrix and other improved cells are presented. The advantages and disadvantages of the current cells are analyzed. According to the demand of TDLAS technology, the trend of optical absorption cells to be smaller, simpler and more stable while measuring multiple gases is pointed out.