Abstract: To address the challenge of accurately identifying and quantitatively evaluating the effectiveness of refracturing in mature shale oil wells in the Ordos Basin, Well YP3 in the X233 Block was taken as the study subject, and a “wellbore reconstruction + bridge-plug joint operation” refracturing scheme was implemented. On the basis, downhole high-definition television imaging monitoring was carried out to systematically record and geometrically measure the perforation holes after fracturing. Based on perforation erosion characteristics, a quantitative evaluation method for refracturing effectiveness was established. The results show that a total of 1,147 high-definition perforation images are acquired on site, with recording and effective measurement rates of 97% and 99%, respectively. After refracturing, the overall perforation hole areas increase, with an erosion rate of 66.1%. All 43 perforation clusters are effectively modified, and the intra-stage perforation erosion distribution exhibits relatively uniform characteristics. Downhole television imaging can intuitively and quantitatively reflect the effectiveness of refracturing in mature shale oil wells. The post-refracturing perforation morphology and erosion characteristics are comparable to those of new wells. It can be used as a reliable technical means for evaluating fracturing effects.