The invention relates to a lithium ion battery cathode material LiNixCoyM1-x-yO2 prepared from micron-sized single crystal particles and a preparation method thereof, wherein x is greater than 0 and is not more than 0.8, y is greater than 0 and is not more than 0.5, and M is one or two of Li, Mn, Al and Mg. The invention is characterized in that (1) composite oxide or hydroxide of transition metal nickel, transition metal cobalt and modified metal M is used as a raw material, the composite oxide or hydroxide is porous aggregate comprising nanocrystals, the average size of the aggregate is 2-50 micrometers, and the specific surface area of the aggregate is greater than 15m<2>/g (measured by BET method); (2) the composite metal oxide or hydroxide and lithium salts are milled in a ball mill, the micron-sized composite metal oxide or hydroxide is converted into nanocrystal particles to obtain a nano-sized mixed precursor of the composite metal oxide or hydroxide and the lithium salts, and the mixed precursor is sintered at uniform temperature to obtain the required lithium ion battery cathode material; and (3) the prepared lithium ion battery cathode material LiNixCoyM1-x-yO2 is basically prepared from micron-sized single crystal particles, and the average size of the single crystal particles is 2-20 micrometers. In addition, the product has excellent physical and electrochemical properties, such as ultra-low specific surface area, reasonable particle size distribution, good electrode processing properties, ultra-long cycle life, excellent rate capability, obvious high and low temperature cycling and storing properties and excellent safety; and the product can be widely used as a high-performance lithium ion battery cathode material. The invention provides the high-performance lithium ion battery cathode material and the preparation method thereof.