：Field-effect transistor (FET) has been widely concerned due to their advantages of fast response, high sensitivity and low cost. Here we fabricate a highly sensitive FET biosensor based on MoS2 nanosheets and explore its application for the detection of bovine serum albumin (BSA). Through hydrophobic interaction, BSA is directly combined with MoS2. The device has a detection limit of 5 nM and a large current response to BSA solution in the range of 5 nM to 5 μM. In addition, by analyzing the transfer characteristic curve of the device and the Raman spectrum of MoS2, we have demonstrated that the reason for the increase of the drain-source current (Ids) is the n-type doping phenomenon of BSA on MoS2. We believe that the MoS2 FETs can be expanded into a universal biosensor platform for the sensitive detection of various biomolecules and are expected to be applied to the highly integrated and multiplexed FETs sensor structure.