The overall aim of this study was to mitigate environmental problems of apartment complexes. Particularly to reduce the effect of heat island which is one of the urban environmental problems. This study focused on the analysis of relationship between heat island effect, and thermal and wind properties. To do this analysis, Green network, which is composed of water space and piloti structure and rooftop greening, was virtually applied to Yeol_Mae village Apt. Because it is very difficult to set up green network to the existing apartment complexes due to realistic constraints, this study has strong sort of guidelines to create green network for newly formed city. It was based on the concept of virtual city through in-depth analysis on reduction of heat island effects for the existing apartment along with creation of green network. To analysis site, Envi-Met Model, developed by Michael Bruse, was used. The results are as follows. The temperature went from298.9Kto 297.82Kand the wind speed went from1.42m/s to 1.43m/s. The changes were slight in this study because creation of green network was planned to small area of an apartment complex. But if green network would be applied to the whole city, the mitigation effect of heat island would be greater.