The invention relates to a quantitative loading system. The quantitative loading system comprises a product oil tank, an oil tank truck and a loading control computer. A control unit I, an IC (integrated circuit) card reader and a receipt printer are respectively connected to the loading control computer. A control unit II, a regulation unit, a control unit III, a mass flowmeter unit and a loading arm are sequentially arranged between the product oil tank and the oil tank truck. The control unit I is respectively connected with the control unit II and the control unit III, the oil tank truck is connected with an electrostatic grounding device, and the control unit I is connected with the electrostatic grounding device. The regulation unit comprises two parallel regulation valves, and the mass flowmeter unit comprises two parallel mass flowmeters. The quantitative loading system has advantages that automatic quantitative loading can be realized, halting caused by inspection of part of parts is avoided, and operation efficiency is remarkably improved.