The constant current driver circuit is designed for vertical cavity surface emitting laser (VCSEL), which is used for online measurement of industrial gases. The structure and the operation principle of the constant current driver circuit are described. The circuit with delay and modulation function can drive the VCSEL safely and reliably. The VCSEL combined with tunable diode laser absorption spectroscopy (TDLAS) technique are used to measure different concentrations of oxygen. The ideal test fitting coefficient proved that the driver circuit is reliable for the VCSEL to control output wavelength. So the constant current driver circuit has potential for industrial gas monitoring actually.