The Box dimension of a class of Weierstrass function f(x)=∑∞ n=1 ancos(λnπx) is discussed.Under the help of the λ-ary expansions,the Box dimension of Γ(f) is 2 when the sequence satisfies limn→∞(an+1/an)=1,where 1λ is an integer and {an} is a summable se...