A numerical simulation method was developed for solving multi-phase flow with mass transfer through the interfaces. The interface is determined by solving the transport equation of marker density function. Surface tension is treated as a body force in the NS equation enjoying porosity concept. Through the interface, the mass of dispersed phase dissolves into continuous phase. As a result, the dispersed phase diminishes its volume. Three case studies were carried out to validate the method. Drop formation simulations demonstrate that the present treatment of the surface tension is accurate enough to simulate the oscillation of drop volume with the increase of flow rate. Simulated dissolution rate from a spherical droplet without flow is in good agreement with the analytical solution. Then the dissolution from a rising droplet is successfully simulated. It is visualized that horse-shoe type vortices are attached by the dissolved mass in the wake of the deformed rising droplet. The resultant Sherwood number agrees well with the solution of an empirical equation.