Shale reservoirs usually have poor physical properties，small pore throats，while conventional measures such as water injection and chemical injection often fail to achieve good development results. CO₂ huff and puff can not only effectively reduce the oil-gas interfacial tension and the viscosity of crude oil，etc，and then achieve the purpose of improving shale oil recovery，but also inject some CO₂ in the formation to achieve permanent storage，which helps to realize the carbon peaks，carbon neutrality. This article used numerical simulation methods to study the adaptability of CO₂ huff and puff in shale oil. Shale reservoirs were mainly composed of micro and nano scale pore throat systems，which generated significant capillary pressure during fluid flow，affecting the thermodynamic phase behavior of crude oil components and subsequently affecting component calculations and fluid flow in porous media. Therefore，nano confinement effect was introduced into the fluid model to simulate the impact of that on fluid component phase behavior through the changes in critical pressure and critical temperature. At the same time，in order to explore the adaptability of CO₂ huff and puff in shale oil under different ratio of fracture network permeability to matrix permeability（Kf /Km） and oil saturation（So）in the increased production area of fracturing transformation，with the increase of recovery degree and oil change rate as reference indicators，the adaptability charts under different Kf /Km and So were obtained. The results showed that compared to not considering the nano confinement effect，the p-T phase diagram of the components considering the nano confinement effect shifted upwards as a whole，meanwhile the bubble point pressure increased. When Kf/Km was 1000 and the increase in CO₂ recovery rate reached 1.5%，the adaptive limit of So was 0.54. When Kf /Km was 1000 and the increase in CO₂ recovery rate reached 2.0%，the adaptive limit of So was 0.57. When So was 0.500 and the oil change rate of CO₂ huff and puff reached 0.3，the adaptability limit of Kf /Km was 700. When So was 0.548 and the oil change rate of CO₂ huff and puff reached 0.6， the adaptability limit of Kf /Km was 10. The Kf /Km-So charts could be used to determine the physical property limits of shale oil’s adaptability to carbon dioxide huff and puff. The research results had certain guiding significance for the design and application of CO₂ throughput field testing schemes.