My research focuses on string theory, especially the quantum gravity aspects of string theory. Apart from the big bang singularity, the black hole is the object where the tension between gravity and quantum physics is the strongest, hence it provides the best stage to test and unlock the full power of string theory. Therefore I am particularly interested in how to understand black holes microscopically using string theory. Recently I have also been working on a toy model of three-dimensional quantum gravities, with the hope of gaining some insight towards higher-dimensional quantum gravities.