The main reasons of attenuation produced during the transmitting of infrared radiation in the atmosphere are introduced, and some usual methods for calculating the atmospheric transmission of infrared radiation and software are briefly shown. The method of using software LOWTRAN 7 and the in-out file formats are described. The importance of application-embedded LOWTRAN 7 is discussed and an application-embedded method of LOWTRAN 7 is put forward. The relevant circuit principle diagram and the subroutine source code programmed using Delphi 6 are given.