Abstract: The characteristics of LPG and its quantitative loading technique are introduced. Analysis and comparison to LPG quantitative loading volume and weighed volume are carried out under the condition of road tankers with same loading capacity but different residual pressure and LPG tank at different pressures, and variable law of metering error is found out. Through studying the process of LPG quantitative loading of road tanker, the origin of metering error produced is determined. Two countermeasures against the metering error are put forward.