An ion beam with different incident energiesEwas used to analyze a 500‐A˚‐thick In0.25Ga0.75As strained epitaxial film grown on GaAs (100) by molecular beam epitaxy. Ion channeling angular scans about ⟨110⟩ axis were carried out in (100) plane. WhenEis 5.8 MeV, the angular misalignment between ⟨110⟩ channels of the top layer and the substrate was 0.90°. We can calculate the planar strain of the epilayer, which is 1.62%. When incident ion energy was decreased, anomalous phemomena were observed in the angular scan profiles of the substrate. WhenEis 3.0 MeV, a serious asymmetry appeared in axial scan profile of the substrate; WhenEis 1.2 MeV, the angular misalignment reduced to 0.60°, and the critical angle for channeling of the substrate is 1.25° which is much larger than that of the epilayer, 0.95°. The physical mechanism giving rise to these phenomena is discussed, and the causes and conditions for these phenomena taking place were pointed out.