Abstract: The article suggests a substitute of vertical tanks with a water cushion at the bottom and a completely tight cover on the oil surface for the inner floating vault tanks, the pneumaticaly immersible pumps in a tank car for the oil unloading pump station with unloading arms. This can thoroughly eliminate the evaporation losses, no problem will arise to bring trouble to oil unloading caused by gas leaking, blocking and corroding in the oil sucking system.