Abstract: The effects of process parameters such as silicon-calcium ratio, reaction temperature, reaction time, water-solid ratio and homogenization speed on the xonotlite slurry during dynamic hydrothermal reaction were studied. The process parameters such as silicon-calcium ratio, reaction temperature, reaction time, water-solid ratio and homogenization speed were determined. The proficiency testing sample of guarded hot plate apparatus thermal conductivity were prepared with the preparation process parameters, and the uniformity and stability were tested. The results show that the uniformity and stability of the sample prepared by this paramenter meet the requirements of the proficiency testing sample, which can be used to evaluate the test ability of guarded hot plate apparatus thermal conductivity in laboratory.