A simultaneous measurement system based on the diode-laser absorption spectroscopy (DLAS) technique is developed to simultaneously measure the thickness and temperature of a dynamic liquid film with high accuracy. The measurement accuracy of this system is validated by a calibration tool and the results show that the average measurement errors of film thickness and temperature are 4.58% and 1.34%, respectively. On this basis, this system is employed to study the evaporation process of the liquid film on a horizontal quartz glass plate and the results indicate that the average evaporation rate of this liquid film is 0.34 μm/s and the evaporation rate increases with the increase of film temperature. Moreover, the results by DLAS, imaging method and thermocouple are well consistent. In addition, the system is applied to the dynamic liquid film in a flow channel and the results disclose that under different film temperatures of 308, 315 and 323 K, the average thicknesses of the liquid film are basically consistent and they fluctuates for 11 times within one second, while the film temperature is almost constant.