Based on that ascending solutions exist in a class of iteratie function equations under the ascending conditiion an that descending iteratice roots exist in a lass of iteratve function equations under ascending conditon,this paper discusses the conditions for te existence of the solutions to the iterative function equation λ1f(x)+λ2f3(x)+...+λnf2n-1(x)=F(x),here F(x) is monotonically descending continuous function,and simply discusses a property of its solution.