The basic principles based on dynamic characteristics of laser speckle for monitoring of the paint drying process was studied. The processing algorithms of realtime detection were analyzed.A differenceaverage algorithm of dynamic speckle was proposed. In this algorithm, gray distribution histogram of the difference image was used to qualitatively describe the strength of the dynamic characteristics of the laser speckle, and the average gray level of the difference image was used to quantitative describes the changes of speckle. Experimental results show that dynamic characteristics of speckle can be used to nondestructive and online monitor the paint drying process, and the differenceaverage algorithm can be given realtime results in the monitoring process with shorter computation time and lower hardware requirements.