The invention relates to a thermochemical blocking type composite positive electrode material, a positive electrode plate and a preparation method therefor, and a lithium ion battery. The composite positive electrode material mainly comprises a ceramic material-coated lithium phosphate positive electrode material and a nickel-cobalt-manganese ternary material at the mass ratio of (5-95) to (5-95); in the ceramic material-coated lithium phosphate positive electrode material, the lithium phosphate is Li<y>M<x>N<1-x>PO<4>, wherein x is greater than 0 and less than 1, y is greater than or equal to 0.8 and less than or equal to 1.2, and M and N are selected from any two kinds of iron, cobalt, nickel, manganese and vanadium; and the nickel-cobalt-manganese ternary material is LiNi<1-x-y>Co<x>Mn<y>O<2>, wherein x is greater than 0 and less than 1, y is greater than 0 and less than 1, and x+y is less than 1. By virtue of the composite positive electrode material, the synergistic thermochemical blocking effect of the ceramic material and the lithium phosphate can be played, so that thermal runaway caused by failure of the positive electrode material structure can be prevented; in addition, the structural stability, the safety and the energy density of the positive electrode material of the lithium ion battery are improved; and furthermore, a simple process, a short process flow and high working efficiency are achieved.