Abstract: Take the oil unloading in wharf of Tianjin Petrochemical Corporation as an example, the paper analyzes the reason of shipping loss of crude oil during shipping. The cause of this kind of shipping loss is consisted of two parts, that is, macroscopic influence and microscopic influence. The former includes the ways of the port of arrival, the differences between different oils in physical behaviors, the way of custody transfer and the seasons of oil unloading; the later includes the insufficiency of oil loading volume in the port of loading over-high water cut or free water of oil shipped, the volume of oil adhered on the bulkhead during the oil unloading and the deformation of cabin due to a long term service, which results in the "increased volume". In the light of crude oil metering during wharf unloading, the suggestions and countermeasures against the shipping loss of crude od are put foreward.