Two presentations of quantum affine superalgebras were introduced by Yamane which were called Drinfeld-Jimbo realization and Drinfeld realization, respectively. Drinfeld realization contains infinite sequences of generators and relations. In this talk, we consider the Drinfeld realization of quantum affine superalgebra $U_q(\hat{sl}_{m|n})$ associated to type $sl_{m|n}$ and define a simple algebra $U_0(\hat{sl}_{m|n})$ generated by only a finite part of these sequences of quantum affine superalgebra $U_q(\hat{sl}_{m|n})$. We show that the algebra ${U}_0(\hat{sl}_{m|n})$ is isomorphic to the quantum affine superalgebra $U_q(\widehat{sl}_{m|n})$. Using the above isomorphism, we prove there exists an isomorphism between the two realizations. This talk is based on the joint work with Prof H. Yamane and Hongda Lin.