This study was investigated effects of the thermal shock resistivity according to the variation of raw material composition ratios and particle sizes in the heat-resistant container. The raw material components were selected by the natural low-grade clay(NLC), the natural low-grade silica sand(NLS) and Talc. Triangular diagram on these three components was constructed for selection of the optimum chemical composition ratios in the heat-resistant containers. As a result of the study, the optimum blending ratio was the condition of NLS(0.42) : NLC(0.33) : Talc(0.25). And as a result of the thermal shock resistivity according to the condition of particle sizes of raw materials, the thermal shock resistivity was increased at the range of particle size under the 70 mesh than the 100 mesh. But the case of manufacturing heat-resistant container in the condition of particle sizes under 70 mesh, salt crystals in the container are permeated into the inner wall and exhausted out the outer wall. Therefore, the container can not maintain the function as a container. Considering the function as a container and the excellent thermal shock resistivity, the optimum condition for the development of the heat-resistant container was the range of particle sizes under 100 mesh and the blending ratio of NLS(0.42) : NLC(0.33) : Talc(0.25) in this experimental condition.