<p>The coupled effects of human activities and rainfall-induced landslide (H-R landslide) are projected to increase around the world, due to the different modes and intensities of their impacts on landslide. it is difficult to quantify the contribution of H-R landslide. The Tangjiawan quarry landslide, which occurred in a mountainous region of southwestern China, on January 28, 2016, was used as a case study. Based on three slope-toe excavation conditions and three rainfall conditions, the nine scenarios (Scenario A - Scenario I) were generated to analyse the effects of human activities and rainfall on landslide. The unstable area of H-R landslide was obtained by accumulating the unstable areas of the geotechnical model and the transient rainfall infiltration model, numerical simulation model was used to simulate the motion and volume of H-R landslide. The results show that the coupling effect of H-R significantly increases the landslide volume, in the most dangerous Scenario I (coupling effect of extreme excavation and extreme rainfall), the landslide volume is 1.5 × 10⁵ m³, which is an increase of 130% compared to extreme excavation Scenario, and an increase of 24.6% compared to extreme rainfall Scenario. In Scenario I, the contribution rate of human activities and rainfall to landslide volume were 0.33 and 0.67, respectively. This study provides a quantitatively method to assess the amplification of landslide volume by human activities and rainfall, as well as the contribution rate of the two in landslide.</p>