Abstract: An experimental device for carbon dioxide imbition, diffusion and oil discharge in a tight oil reservoir includes: a multistage rock core holder connected with a confining pressure pump and including a pair of connecting holes arranged at an upper end and a lower end thereof with an oil filler pipe connecting therebetween, a crude oil injection device and a recovery device respectively connected to the upper and lower ends, an intermediate container connected to both a high-pressure cylinder and an injection pump, a return pressure pump, a collection device and a control system. A plurality of rows of openings is arranged at a side of the multistage rock core holder to act as a gas inlet connected with the intermediate container via a pipeline, and a gas outlet connected with the recovery device; heating layers are arranged at inner walls of the multistage rock core holder and the intermediate container.