Magnesia, acted as a refractory material, is widely used in industrial metallurgical furnaces owing to its high refractoriness and excellent corrosion resistance to basic slag and metal melt. Generally, the fabrication of high-quality magnesia aggregates with high purity and high bulk densities (＞3.40 g/cm3) plays a critical role in producing MgO-based refractories that show satisfying mechanical properties and corrosion resistance. In China, magnesite is mainly used as a raw material to produce sintered magnesia at high-temperature. while, as the generally coarse-grained of magnesite, it is difficult to produce high density magnesia even sintered at high temperatures, being due to the poor sintering property. As reported that the introduction of oxides additives such as TiO2, Al2O3 ZrO2, etc. could effectively promote the sintering of magnesia. However, the additives also resulted in a low melting phase formation, which significantly reduced the high-temperature performance of magnesia. In fact, besides magnesite, China also has abundant magnesium resources in salt lakes. Compared to magnesite, magnesia derived from salt lake owns the advantage of higher purity and without CO2 emissions during the production process. In this work, magnesium hydroxide produced from salt lake was used as raw material to prepare the high-purity dense magnesia via a two-step method. Effects of calcination temperature and grinding time on the morphology and sintering activity of MgO were studied, microstructure and densification behavior of magnesia sintering at high-temperature were investigated also.