Using SiO2, CaO and MgO as main raw materials, basic glasses were prepared by traditional high temperature melting process, and diopside glass-ceramics were prepared by one-step crystallization heat treatment method. The effects of heat treatment temperature and time on crystallization and thermal conductivity of diopside glass-ceramics were studied by X-ray diffraction, scanning electron microscope and laser thermal conductivity meter respectively. The results show that with the increases of heat treatment temperature, the crystallinity of glass-ceramics increases, the grain size increases, and the thermal conductivity first increases and then decreases. With the increases of heat treatment time, the grain size of glass-ceramics increases, and the thermal conductivity first increases and then decreases. When the heat treatment temperature is 890 ℃, the heat treatment time is 120 min, the heating rate is 10 ℃/min, the grain size of glass-ceramics is 0.3-0.4 μm, the crystallinity is 79%, and the thermal conductivity reaches the maximum value of 2.59 W/(m?K).