Local-gate multilayer MoS2 phototransistors exhibit a photoresponsivity of up to 342.6 A W-1, which is higher by 3 orders of magnitude than that of globalgate multilayer MoS2 phototransistors. These simulations indicate that the gate underlap is critical for the enhancement of the photoresponsivity. These results suggest that high photoresponsivity can be achieved in indirect-bandgap multilayer MoS2 phototransistors by optimizing the optoelectronic design.