The embodiment of the utility model provides an oil sampling device which comprises a round disc arranged on an oil outlet of a sampling valve of a transformer, a first tubular channel which is connected with the round disc and a second tubular channel which is connected with the first tubular channel. According to the oil sampling device provided by the embodiment of the utility model, a steel ball arranged in the second channel blocks a channel port of the second channel under the action of the elasticity of a spring, thus sealing an oil sample; meanwhile, by rotating a ball valve, an ejector rod which is connected with the ball valve in a third channel can push the steel ball blocking the oil outlet of the second channel to enable the oil sample in the second channel to flow into an oil cavity arranged in the third channel; and due to a through hole formed in the outer surface of the ejector rod, the oil sample in the oil cavity can flow into a through pipeline in the ejector rod and enters the ball valve connected with the ejector rod through the through pipeline, the oil sampling port of the ball valve is opened, and the oil sample can be taken. With the adoption of the oil sampling device, the oil sampling operation is convenient.