The invention discloses a lithium ion battery positive paste and a preparation method thereof. The lithium ion battery positive paste comprises based on parts by weight: 87-93 parts of positive active substance, 2.6-7 parts of conductive agent, 3-5 parts of binding agent and 49-60 parts of solvent, wherein the positive active substance comprises lithium nickel manganese cobalt and lithium iron phosphate; based on parts by weight, the lithium nickel manganese cobalt accounts for 6-10% of the lithium iron phosphate; the binding agent is one of polyvinylidene fluoride (PVDF) resin or polyvinylidene fluoride; the conductive agent is one or more of a carbon nanotube, carbon black or graphite; and the solvent is N-methyl pyrrolidone. By the lithium ion battery positive paste and the preparation method thereof, the lithium iron phosphate and the lithium nickel manganese cobalt are mixed according to a certain proportion to prepare the lithium ion battery positive paste, and the safety of a battery is improved by means of high safety performance of the lithium iron phosphate; and the lithium nickel manganese cobalt is added into the lithium iron phosphate, the defects of low content and low electrical conductivity of the lithium iron phosphate are overcome to a certain extent, the electrical conductivity of the battery is improved, and large-current charging and discharging of the battery can be achieved.