The shadow of the Moon observed with cosmic rays can be utilized to study the pointing error and the angular resolution of the ground-based air shower arrays, also offers a good ability to do below a few TeV energy calibration based on the bending of cosmic rays when they travel through the geomagnetic field. Water Cherenkov Detector Array (WCDA), one of components of Large High Altitude Air Shower Observation (LHAASO), has high observation sensitivity, lower threshold, and high duty cycle, which make itself a very good facility in this aspect. In this presentation, we study the ability of the westward displacement of the Moon shadow based on
an accurate simulation and experimental data analysis, some systematic uncertainties related with energy calibration are also discussed.