Effect of cerium content on phase structure, electrochemical properties and pressure concentration temperature ( P C T ) characteristics of Ml (NiCoAlMn) 5 alloy ( Ml =Michmetal) has been investigated. Experimental results indicate that as cerium content increases, the lattice constants ( a,c ), cell volume ( V ) and axis ration ( c/a ) of the alloy decrease; the elemental segregation in dendrite increases; the discharge capacity decreases; the cycling stability increases; the plateau pressure of P C T curve increases. The alloy with 15 at% Ce has optimum comprehensive electrochemical properties.