With the advantages of low noise, low infrared characterization and high dependability, proton exchange membrane fuel cells (PEMFC) are widely used in hybrid electric vehicle. Internal reaction environment of PEMFC has great influence on its property and service life. Aiming at the operation features of air-cooled PEMFC, a temperature and humidity matched optimal control is improved. A dynamic reaction speed control mode is proposed, which avoids water excursion caused by steadily control and improves voltage coherence of fuel cells. Finally the feasibility is validated through experiments on small PEMFC prototype.