In this talk, we will first introduce the notion “fill-in with nonnegative scalar curvature”. Then we will talk about the motivation of this fill-in problem both from geometry of compact manifold with boundary and quasi-local mass in the general relativity. In the end, we will review some questions raised by Gromov and some results in this direction. The talk is based on joint works with Prof. Yuguang Shi, Dr. Guodong Wei and Jintian Zhu.