In order to calculate Terahertz(THz) wave atmospheric absorption loss accurately, THz propagation segmented path model should be established firstly, and continuous changing environmental atmospheric parameters can be obtained through the whole path. Each segment path’s atmospheric absorption loss is obtained by using International Telecommunications Union-Radio communications sector(ITU-R) standard, and the whole segments are accumulated to get total atmospheric absorption loss. It is difficult to obtain complete atmospheric parameters along the propagation path due to the lack of meteorological observation equipment and methods. Besides, atmospheric refraction effect appears due to the earth’s gravity, which makes curved THz propagation path. This paper discusses the calculation method of THz wave atmospheric absorption loss. Based on atmospheric observation re-analysis data, using ITU-R standard as bridge, a constructive relationship is built between meteorological data and atmospheric absorption loss. The proposed method can be used in the ground detection engineering of THz wave for aircraft, to make THz communication link’s atmospheric absorption loss estimation.