Abstract: Based on quality evaluation, deformation review and slope stability analysis against sliding of Menlou reservoir main dam, its structural stability was evaluated. The evaluated results showed that the main dam slope stability against sliding could meet the regulatory requirements, the reservoir bank near the main dam was basically stable, but the depression existed at the upstream slope with poor placement quality, and the sand grain material of the upstream dam shell with the potential seismic liquefaction was possibly liquefied soil.