Abstract: This paper briefly describes the development history and current situation of tank metering techniques as well as the characteristics of each development stage. Disadvantages of traditional tank metering techniques and advantages of new tank metering techniques are presented by comparative analysis, demonstrating the necessity of promoting automatic tank metering techniques. Advantages of online servo densitometers and the feasibility of their application in automatic tank metering are illustrated through application examples. Considering the current situation of various oil depots, this paper identifies some problems in automatic tank metering and makes some suggestions on promoting applications of online densitometers.