The MEG experiment, which searches for a lepton flavor violating muon decay, μ → eγ, to explore new physics like supersymmetric grand unification, has started physics run since 2008 at Paul Scherrer Institute, Switzerland. Its innovative detector system, which consists of a 900 liter liquid xenon scintillation photon detector with 846 2 inch photomultiplier tubes and a positron spectrometer with a superconducting magnet, drift chamber, and timing counter, enables orders of magnitude better

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... tivity than previous experiments. The liquid xenon gamma-ray detector is a crucial component for our experiment in order to reduce the accidental background and to achieve our goal of sensitivity. Several purification methods including gaseous and liquid phase have been done to increase the scintillation light yield, and various calibration and monitoring methods to evaluate the detector performance have been tried and established. The current performance of the liquid xenon detector for physics analysis and some future prospects are described here as well as the calibration and monitoring methods.