Highly-concentrated industrial wastewater is difficult to be treated with general biological and physical method. The wastewater treatment with spray drying method is expected to have the advantages of low energy, cost and no discharge from the system. CFD simulation software(Fluent/Uns 4.2) was used to predict gas and droplet flow, heat and mass transfer in the reactor. The reactor has the shape of cylinder which is 7 m in height and 0.78 m in diameter. Hot gas(400K, air) blows and the nozzle sprays with water from the bottom to the top (Wet Gas Outlet) of the reactor. The result showed particle residence time, vaporization rate, velocity, path line and temperature distribution. The residence time of droplets was not uniform and distributed for 17.5 sec. Only 8.17 % of total mass wasevaporated. Most of droplets were vaporized near the hot gas inlet. Moreover, there was heat loss to the solid particle oulet. Due to the vortex, saturated air could not leave the reactor.