A power supply device with PCB-positioning features includes a casing, a PCB (Printed Circuit Board) and at least one pair of slots. The casing defines an accommodating space and has at least one opening. The PCB is disposed in the accommodating space and has electronic elements thereon. The at least one pair of slots is disposed at inner walls of the casing for positioning the PCB. A gel-fillable channel is defined between the electronic elements and the inner walls of the casing.