High-strength ceramsite was prepared by using demagnesium boron mud and oil shale (OS) semi-coke as the main raw materials, NaSiO as binder, and NaCO as foaming agent. In the ceramsite with a 1:1 ratio of demagnesium boron mud and OS semi-coke, 3% NaSiO, and 10% NaCO sintered at 1070C, the porosity, apparent density, and compressive strength reached 22.63%, 1398.33 kg/m and 11.50 MPa, respectively. NaCO played a decisive role in the sintering of high-strength ceramsite. Thermogravimetric analysis and X-ray diffraction results showed that the gas produced by raw meal during the heating process reduced the apparent density of ceramsite, and that new minerals such as albite and forsterite were produced during the firing process. The forsterite formed islands within an albite framework, thereby strengthening the ceramsite.