Tight reservoirs are typically developed through large-scale hydraulic fracturing to effectively connect natural fractures， which significantly influence CO₂ huff-n-puff oil recovery. To clarify the characteristics of oil mobilization under different fracture conditions in tight reservoirs，CO₂ huff-n-puff nuclear magnetic resonance（NMR）experiments were conducted for varying fracture apertures，as well as microscopic visualization experiments under multi-scale fracture conditions. The effects of fracture aperture and fracture density on CO₂ huff-n-puff performance were systematically investigated. The results showed that under single fracture conditions，an increase in fracture aperture significantly enhanced the oil recovery degree of both fractures and surrounding matrix. When the fracture aperture increased from 20 μm to 70 μm，the cumulative oil recovery degree after four cycles of CO₂ huff and puff improved by 9.20 percentage points. Under multi-scale fracture conditions，an increase in fracture density enhanced reservoir connectivity and expanded the sweep area of CO₂. Compared to simple fracture model，the matrix oil recovery degree in complex fracture model increased by 4.26 percentage points after four cycles of CO₂ huff and puff. The enhancement in recovery factor of multi-scale fracture primarily occurred during the first two huff-n-puff cycles，with the incremental oil recovery effect diminishing in subsequent cycles. Increasing fracture aperture and fracture density could effectively improve matrix oil mobilization in tight oil reservoirs. The research results could provide theoretical guidance and technical support for enhancing oil recovery of CO₂ huff and puff in tight oil reservoirs.