Silico-manganese slag is a main solid waste produced from production of silicon-manganese alloy, which affects the environment. It is thus necessary to explore the corresponding disposal methods since the exsiting processing technology restricts the absorbing capacity. A microcrystalline cast stone was fabricated by the Petrurgic firing method with silico-manganese slag as a raw material. The bulk density, microhardness, flexural and compressive strength of the samples were determined. The influences of crystallization temperature and time on the phase structure and properties of the finished product were invesigated. The results show that a hot molten slag is cooled to 950 ℃ for 60 min and then annealed at 760 ℃ , obtaing a microcrystalline cast stone with the superior properties. The microcrystalline cast stone has a compact structure, and the precipitated crystal phases are mainly clinopyroxene, diopside and aluminum diopside, as well as anorthite and wollastonite. The bulk density of the cast stone can reach 3.11×10³ kg·m^–3, the microhardness is 8.77×10³ MPa, and the flexural strength and the compressive strength are 86 MPa and 222.9 MPa, respectively.