The present disclosure provides a cathode active material and a lithium ion electrochemical system including the same. A general formula of the cathode active material is as follows: z{xLi2MnO3*(1−x)LiRO2}*(1−z) LiaR′1-aOy, herein R and R′ independently include one or more metal ions, an oxidation valence state of the R is 3+, and an oxidation valence state of the R′ is 2+, herein, 0≤x≤0.25, 0