Abstract: Both the vertical metal tank and flow meter are used as a means to measure liquid oil products at delivery. The vertical tank measuring crrors as specified in the Regulations for Measurement at delivery promulgated by the Ministry of petroleum Industry are 0.35%, but the paper notes that, in addition to 0.35%, there are quite a few variable factors affecting the measuring accuracy, Through comparisons between tanks and flow meters in measurement, there has come the conclusion that the date taken by a tank is 0.16-0.41% less than that by a flow meter. Therefore, if condition permitted, flow meter be should selected for measurement at delivery.