Efficient preparation of two-dimensional materials is still a great challenge. These materials possess unique electrical, optical, and thermal properties. In this study, few-layer MoS2 nanosheets and nanoflakes were exfoliated by the hydrolysis reaction of LiBH4. First, the layered MoS2 powder materials were mixed with LiBH4 to obtain a homogeneous powder mixture, and then the mixture was heated above the melting point of LiBH4 under 300 °C and 4 MPa H2 for 2 h, during which the layered materials were curled by liquid LiBH4. In the subsequent hydrolysis of LiBH4, the layered materials were split into nanosheets by H2 gas generation. The obtained MoS2 nanosheets show almost uniform thickness of ~4 nm, with a width of 2-10 μm and a yield of more than 1.5 wt.%. The effectiveness of this method has also been verified by the preparation of few-layer h-BN. This work provides a new high-yield route to producing two-dimensional materials.