At present, we are taking more and more attention on environment protecting, food and medicine safety, and more researching and applying on green printing and packaging technique has been done abroad. Around these, water-based ink has been accepted by the market step by step, but the printing press on this area still with some problems: Lower drying efficiency and lower printing speed. To solve these problems, we analysis the hot-air drying process based on model Logarithmic. We suppose the experiment environment as follow: the temperature is 50°C, the hot air speed is 6m/s, meanwhile we suppose the experiment keep to second Fick-law: The liquid equally distributing around the solid at the beginning; during the drying process, the diffusing modulus keep steady; the resistance of external diathermanous medium is ignored and keep linear diffuse. Under this experimental condition, we record the data about the volume of liquid in the solid during the process, and then analyze the data by the software SPSS, we evaluate the model by the square of relating parameters, and then revise the model so that it can keep the same with the drying process. The model can forecast the drying rate of the water-based ink. This model can supply basal dada for the designing work of water-based ink; at the same time, it has actively influence on speedup the printing press.