Belonging to the field of new materials and electrochemistry, the invention discloses a preparation method of a lithium ion battery novel cathode material. The method includes: taking an iron salt, ammonium fluoride and urea as the raw materials, adopting a porous foamed nickel net as the current collector, employing a hydrothermal reaction method and combining a subsequent chemical vapor carbon deposition method to prepare an Fe3O4 based battery electrode material with a three-dimensional space conductive network in situ. The method provided by the invention has the advantages of low raw material price, simple preparation process, short time and high yield. The carbon coated Fe3O4/Ni/C composite cathode material prepared in situ shows tidy nano-sheet layer array structure and all grows on an Ni net matrix uniformly, and has high loading capacity and good rate performance. The initial discharge specific capacity and initial charge specific capacity are 1184 and 816 mAh g<-1>, and the Fe3O4/Ni/C composite cathode material shows good electrochemical performance.