The invention relates to a method and a device for improving the oil-supplying reliability of a lubricating-oil system of a power generating set. The method is characterized in that in a control logic of a DCS (Distributed Control System) of the lubricating-oil system of the power generating set, when the low voltage of a safety section is related to tripping, additionally setting time delay of 2-5 seconds for an alternating-current lubricating-oil pump, so as to avoid the voltage-loss time of the alternating-current lubricating-oil pump for 1-2 seconds when a power switch of the safety section is switched, and ensuring no tripping of the alternating-current lubricating-oil pump when the power switch of the safety section is switched; setting a low-voltage instantaneous linked starting condition of the safety section in the hard-wiring condition of related starting of a direct-current lubricating-oil pump, setting a low-voltage instantaneous starting condition into failure of the alternating-current lubricating-oil pump in the linking logic of the direct-current lubricating-oil pump, and ensuring that oil pressure is provided by the direct-current lubricating-oil pump when in short-time voltage loss of a power switching bus of the safety section. The method and the device have the advantages that the oil-supplying reliability of the lubricating-oil system of the power generating set is improved from two aspects, the reliability is high and normal oil supplying of the lubricating-oil system at the low voltage of the safety section and under the condition that the alternating-current lubricating-oil pump fails is ensured.