Debris flow is a multiphase mixture, which consists of water, fine particles (e.g., silts and clays) and coarse particles (e.g., sand, gravel and boulders), leading to complex abrasion processes on concrete structures that cannot be fully simulated by conventional abrasion testing methods. In this work, a rotating drum abrasion apparatus is developed to simulate concrete abrasion damage caused by debris flow, and the optimal conditions for improving abrasion efficiency are determined. The effects of abrasive particle types (limestone, steel ball), particle sizes (10 mm, 15 mm, 20 mm), debris flow velocities (3 m/s, 4 m/s, 5 m/s), and debris flow types (diluted debris flow, viscous debris flow) on the abrasion resistance of concrete are investigated. The results show that viscous debris flow with higher bulk density leads to more severe abrasion damage of concrete. The abrasive mass increases with the increase of size and velocity of abrasive materials, ranging from 195 % to 244 %, compared to the control concrete. The concrete abrasion damage caused by debris flow mainly exhibits coarse aggregate cutting, mortar detachment, and fine aggregate stripping. Microscopic abrasion analysis indicates that the obvious rough surface with visible microcracks is observed on the mortar matrix. The optimized abrasion conditions for the developed rotating drum abrasion apparatus are obtained, i.e., viscous debris flow with a bulk density of 1.9 g/cm3, a velocity of 5 m/s and steel balls with a size of 20 mm. The results provide a new apparatus and method for concrete abrasion tests caused by debris flow, which significantly improves abrasion testing efficiency under solid-liquid coupling conditions.