Let p≥7 and q=pm. is the Kloosterman sum of a on Fpm, where . The value of Kq(a) and its conjugate have close relationship with a class of binomial functions with Dillon exponent. This paper first presents some necessary conditions for a such that . Further, we prove that if p=11, for any a , . And for p≥13, if a∈Fps and s=gcd(2,m), . In application, these results explain that some class of binomial regular bent functions does not exist.