The invention discloses a composite vanadium extraction and dephosphorization agent for vanadium-bearing molten iron and a method for preparing the same. The composite vanadium extraction and dephosphorization agent comprises the following compositions in percentage by weight: 0 to 30 percent of CaO, 40 to 65 percent of TFe, 3 to 15 percent of SiO2, 0 to 15 percent of MgO, 0 to 15 percent Al2O3 ofand the balance being impurity. Through utilizing the composite vanadium extraction and dephosphorization agent, the pretreatment of vanadium extraction and dephosphorization can be carried out to the vanadium-bearing molten iron by one-step operation, thereby extracting a beneficial element of vanadium and acquiring low-phosphorus semisteel.