The concept of topology in condensed matter physics has won the 2016 noble prize in physics. Usually, topological band theory is attributed to electronic systems only. Recently, researchers have extended the concept of topological condensed matter to non-electronic systems such as spin waves in quantum magnets (magnon) and mechanical waves in solids (phonon). In this talk, I will give a general exposition of topological magnon insulators and magnon Hall effect in quantum magnetic systems, in which the Dzyaloshinskii-Moriya interaction (DMI) is the driving force similar to spin-orbit coupling (SOC) in electronic systems. I will also discuss recent experimental realizations of this phenomenon. In the last part of the talk, I will show that the DMI or SOC is not the primary source of topological spin excitations in magnetic systems with spin frustrations. This interaction can be zero and topological spin excitation still persists. This is in sharp contrast to previous experimental reports in insulating ferromagnets Lu2V2O7 and Cu(1-3, bdc).