Improved oil storage tank dehydration valve group

The invention relates to an oil storage tank dehydration valve group which can determine that whether a discharged substance is oil or water. The oil storage tank dehydration valve group comprises an oil storage tank, a water cutting opening and a water cutting straight pipe, wherein the water cutting opening is formed in the side wall of the oil storage tank, and the water cutting straight pipe is connected with the water cutting opening by virtue of a one-time water cutting valve; the water cutting straight pipe is connected with a second-time water cutting valve by virtue of a pipeline; an observation mirror is additionally arranged on one end of the water cutting straight pipe, which is far from the oil storage tank, an observation floating ball is added into the observation mirror, and the floating ball is marked with a water mark by using a red pen in advance when a medium is water; when oil flows out, the oil floods a water line of the floating ball, so as to recognize an oil and water layered interfac