The invention provides a LiNi0.5Mn1.5O4 material, a preparation method thereof as well as a lithium ion battery. The method comprises the following steps: preparing a superfine manganese dioxide nanowire by adopting a hydrothermal method, uniformly mixing a manganese dioxide nanowire precursor with a lithium salt and a nickel salt according to a certain ratio, calcining in air to obtain a LiNi0.5Mn1.5O4 nanorod which is uniform in distribution and small in size. The used raw materials are low in price, the environmental pollution is avoided, and the process is easily controlled and suitable for large-scale industrial production. The lithium ion battery made of an anode material prepared by the method has the discharge specific energy of more than 480Wh Kg<-1>, and when the charge and discharge frequency is 500 times, the capacity retention ratio and efficiency are kept over 99%.