Abstract: At present, domestic pipeline transportation enterprises and refinery enterprises mainly use flowmeter coefficient interval method on crude oil custody transfer metering.In order to eliminate the drift error of flowmeter characteristic curve, correction is done by calculating the mean value of two calibration coefficients.The subtraction of the real custody transfer amount and the amount by basic error method during two calibrations follows the "back much & little repair" rule at the end of each time oil settlement after flowmeter calibration.This paper provides the oil amount formula and read rule of metering parameters.Associated with the practical example, the overall calculation procedure is introduced for crude oil metering settlement with this method, including the calculation of coefficient M_F of a flowmeter under a specific displacement, crude oil volume pressure correction coefficient C_pi.crude oil volume temperature correction coefficient C_ti, crude oil standard volume under 20 ℃ V₂₀, mass of water-cut crude oil m.pure oil mass m_a, water amount m_s and make up difference oil m_B. Also, the reasons of custody transfer error produced are analyzed, including the property and temperature of crude oil, pipeline operation pressure, running status of metering devices and personal factors.The error control solution is presented, which is of significance in crude oil custody transfer operation.