In the article research results are presented, which aim to provide of automation algorithm mathematical model of designing technology clothing of the cold protection. The method of calculating heat transfer in the "human - environment" system takes into account the variable thermal parameters and the geometric dimensions of the elements, the presence of internal heat sources and convective heat transfer with the heat-carrier flow along the layers and between the calculated elements . Then the problem is reduced to a one-dimensional heat conduction problem with a variable thermal conductivity coefficient. When modeling a human body, we assume that each element of the model is represented as a set of elliptical cylinders forming the inner layers. Four main concepts of the geometric representation of the outer and inner solutions of the human body model have been developed to simulate the problems of human heat exchange with the environment. An algorithm is proposed for determining the type and structure of a mathematical model for use in CAD systems of protective clothing designing. The research was made in Don State Technical University within the framework of State Assignment of the Ministry of education and science of Russia under the project 11.9194.2017/BCh.