Inner oil tank with corrugated bag and for buoyancy adjustment

The invention discloses an inner oil tank with a corrugated bag and for buoyancy adjustment. Through extension and contraction of the corrugated bag, the volume of hydraulic oil of the inner oil tankis changed, and the operation action is reliable. The inner oil tank specifically comprises an oil tank body, the corrugated bag, an air pressure detection unit and a pull rope displacement sensor; during oil discharging, gas with set pressure is injected into an inner cavity of the corrugated bag, then an execution element is started, oil is discharged into an outer skin bag through an air discharging port, the corrugated bag extends along with the hydraulic oil under the effect of gas pressure of the inner cavity, in the process, the pull rope displacement sensor measures the movement strokeof the corrugated bag in real time, and after the corrugated bag reaches the set stroke, the execution element is closed, and oil discharging is stopped; during oil returning, the gas of the inner cavity of the corrugated bag