The subject of research: is a mathematical model of thermal conductivity in a porous flat wall, the structure of which is based on the three times periodic minimal Sean surface I-WP(TPMS). The purpose of research: to study the course of the heat conduction process in a porous plate at a given porosity. At the same time, the material from which the porous plate is made is PETG plastic. Methods of research: in this work, the solution was carried out by the finite difference method in the Mathcad software. Results of the research: temperature distributions were obtained along the spatial coordinate and in time, as well as the distribution of heat flow in time depending on the change in the plate porosity coefficient.