The ultra fast outflows (UFOs) in AGN are potentially the most effective process for
transporting energy to their host galaxies, so that they are considered to play an
important role in the coevolution of supermassive black holes and galaxies. However, the
physical properties of UFOs are still unknown. We have constructed a new X-ray spectral
model for the AGN outflows, and applied it to the multiple observational data. Our new
code can calculate the radiation transfer in the realistic 3-dimensional geometry of the
accretion disk winds by utilizing Monte Carlo method. Our spectral model successfully
reproduces the emission lines as well as the absorption lines of H/He-like Fe
ions. Moreover, we found that the observed spectral variability can be explained by
changing only a few parameters.