In this article, we would like to estimate the surface temperature and heat flow pattern of the four corner walls of building envelope with thermal bridge. In doing so, this study made use of infra-red camera and the heat transfer simulation. The field measurement using infra-red thermography shows thermal bridge and thermal insulation performance of each part of actual existing building envelope. The heat transfer simulation program calculated 3-D steady state heat transfer properties in the corner walls of building envelope as boundary condition (structure shape, thermal insulation, ambient temperature). Through this study, we provide the mathematical models for estimating thermal bridge effect of the corner walls per boundary condition and we expect to contribute to the effecitve evaluation of thermal performance of the building envelope.