Abstract: XENON1T is a low background dark matter search experiment located at Gran Sasso Underground Lab in Italy. The recent announcement of the observation of low energy excess events in XENON1T triggered many investigations of its origin. In this talk, I will give a brief introduction of the experiment, then explain a few possible origins of these events,  from previously unknown background to new physics. Prospect of disentangling these possible explanations with the upcoming XENONnT experiment will be presented in the end.