Although pulse combustion drying would exhibit high rate of mass transfer when used in a drying process, there is no numerical research about the mass transfer between materials and unsteady flow generated by pulse combustor. The results of an investigation of the moisture diffusivity in refractory clay and the convection process of moisture between refractory clay and outflow was reported. A Helmholtz type pulse combustion was used to generate an oscillating airflow. The moisture diffusivity in refractory clay was determined by the simplified method of drying methods. The mass transfer coefficient between refractory clay and outflow was evaluated by the results of experiment and Fick’s second law with reasonable initial conditions and boundary conditions. The effect of airflow oscillating frequency on mass transfer coefficient was investigated and the correlation was established.