Electron-beam irradiation (EBI) is an effective approach to engineer defects for two-dimensional (2D) materials. However, a detailed understanding of the effects of EBI on charge transport of 2D materials is still lacking. Herein, the value of source-drain current of monolayer MoS(2)transistors can be largely improved by about 3 orders of magnitude under EBI, from 5 nA to 24.6 mu A at 2 V bias voltage. In addition, a room-temperature mobility (mu) as high as similar to 83 cm(2) V-1 s(-1)was achieved when the device was irradiated for 80 s with a 10 kV accelerating voltage (similar to 5.5% sulphur vacancies), far exceeding (about 80 times) that of the untreated device. The improvements of electrical properties after EBI are mainly attributed to the introduction of electrons and the enhanced charge transport channels. The charge transport behaviour under EBI exhibits variable range hopping associated with temperature. Our findings provide an avenue for building high performance electronics based on 2D materials.