Angle factors between enclosure structural surfaces, or between human body and enclosure structural surfaces are the basic parameters to calculate radiant heat transfer in a radiant air-conditioned room. At present, the angle factors between the human body, radiant panels, windows and doors are usually quite difficult to solve. Therefore, we derived the angle factor expressions of two rectangular surfaces in the positions both mutual perpendicular and mutual parallel by using curve integral formula of angle factor, instead of using conventional surface integral formula. Meanwhile, angle factors between human body and enclosure structural surfaces by simplifying a seated person as a rectangular solid were acquired. The results were shown to be efficient and practical, and were free from the limitation of envehpe sizes and relative positions.