The invention provides a lithium ion battery, a composite doping modified positive electrode active material thereof and a preparation method. The general formula of the composite doping modified positive electrode active material is LirQ<1-x>MxVO<4-y>Ny, wherein M and N are doping elements; Q is one of Co, Ni, Mn, Cr, Al, Mg, Fe and Cu; M is at least one of Co, Ni, Mn, Cr, Al, Mg, Fe, Cu, Zr, La, Ti, Ca, Ba, B and Si; N is at least one of F, Cl, Br, I, olivine polyanions and acid radicals; r is more than 0.6 and is not more than 1.05; x is more than 0 and is not more than 0.25; y is more than 0 and is not more than 0.30; Q and M are not the same; an X-ray diffraction (XRD) pattern of the composite doping modified positive electrode active material comprises a strongest diffraction peak (311) and characteristic peaks of inverse spinel, namely a weak peak (111) and a moderately strong peak (220). The lithium ion battery comprises the composite doping modified positive electrode active material. The composite doping modified positive electrode active material has a stable structure and good morphology. The first discharge operating voltage platform, the first specific discharge capacity, the first coulombic efficiency and the capacity retention ratio after multiple cycles of the lithium ion battery are higher.