To investigate the reason for the reduction in damage resistance of In x Ga1−x N with increasing indium (In) content, we used molecular dynamics methods to simulate the threshold displacement energies, the individual recoil damage and the overlapping cascade processes in In x Ga1−x N (x = 0.3, 0.5, 0.7) during ion implantation. The average threshold displacement energy of In x Ga1−x N decreases a little (from 41.0 eV to 34.6 eV) as the In content increases (from 0.3 to 0.7) and the number of defects produced by individual cascades increases less than 30% with increasing In content (from 0.3 to 0.7), while the overlapping cascade simulations showed that with In content increasing the dynamic annealing processes in cascades were significantly suppressed. Thus, the suppression of dynamic annealing in the cascades is the main reason for the reduction of damage resistance of In x Ga1−x N by adding In content. The analysis of defect distribution during overlapping cascades showed that defects in In-rich In x Ga1−x N (x = 0.7) agglomerate more rapidly as the irradiation dose increases and are likely to form large clusters, which are harder to anneal during cascade evolution. Therefore, the suppression of dynamic annealing in In-rich In x Ga1−x N can be attributed to the rapid agglomeration of defects with the irradiation dose.