In order to realize mass transfer analysis for microwave hot in-place recycling of asphalt pavements,a volume element is established including asphalt mixtures,liquid water and vapor.A mass transfer control model is built by the theory of multiphysies,phase transformation and diffusion.The model contains continuity equation,energy conservation equation,movement equation and vapor diffusion equation.To gain the solution of the mass transfer model,the formulas are simplified to one-dimensional differential equations.And then a mathematical model of boundary conditions is established.The mass transfer velocity and dissipative energy are obtained in different moisture contents through simulation of asphalt pavements recycling.The result indicates that when initial moisture content is certain,mass transfer velocity is almost uniform in depth direction at the same heating time and energy absorbed by water is descending with depletion of moisture.