The invention provides a composite positive electrode active material and a lithium ion secondary battery. The composite positive electrode active material comprises positive electrode active material particles, and a coating material which is positioned on the external of the positive electrode active material particles for coating the positive electrode active material particles. The positive electrode active material particles are layered lithium composite oxide; the general formula of the layered lithium composite oxide is Li1+xNiaCobM (1-a-b)Y2, wherein x is greater than or equal to minus 0.1 and less than or equal to 0.2; a is greater than or equal to 0 and less than or equal to 1, b is greater than or equal to 0.05 and less than or equal to 1, and a+b is greater than or equal to 0.05 and less than or equal to 1; M is selected from one or more of Mg, Zn, Ga, Ba, Al, Fe, Cr, Sn, V, Mn, Sc, Ti, Nb, Mo or Zr; Y is selected from one or more of O, or F; the bulk structure of the coating material is P4 / mbm space group; and the lithium ion secondary battery comprises the composite positive electrode active material. The lithium ion secondary battery is higher in energy density and better in cycle performance under high voltage.