Controlling oxygen concentration in heating furnace is the most important factor in the steel making progress. Tunable diode laser absorption spectroscopy sensor is applied to measure the oxygen concentration and temperature in lab-scale electric furnace. A DFB type diode laser of 760nm line centre frequency is used to measure oxygen concentration and temperature is measured using a pair of oxygen transitions near 760nm Scanned-wavelength direct absorption spectroscopy method is applied and experimental data are obtained. As part of the sensor development effort, fundamental spectroscopic parameters including the line strength, absorption, line centre frequency are measured to improve the current databases.