For an even integer

n

not less than 4

a sufficient and necessary condition was established for constructing a Bent function in

n+

2 variables from 4 Bent functions in

n

variables.An iterative construction of Bent functions was proposed to construct (

n

+2)-variable Bent functions from

n

-variable Bent functions.The algebraic degree of some Bent functions constructed by the proposed method was also analyzed.The iterative method unifies and generalizes two previous constructions of Bent functions.