Objective To evaluate the value of routine magnetic resonance (MR) scanning and 3D FIESTA sequence in the early prognosis of the endoscopic third ventriculostomy. Methods The clinical materials of 17 cases of obstructive hydrocephalus treated with endoscopic third ventriculostomy (ETV) in the Nuclear Industry 215 Hospital of Shaanxi Province between January 2020 and December 2023 were analyzed retrospectively. Preoperative and early postoperative (within 1-month) routine MR imaging (T1WI, T2WI, Flair) and 3D FIESTA imaging were performed simultaneously. The patients were divided into improved group and unchanged group according to the size change of the ventricular system (Evans index), the degree of periventricular interstitial edema and the displacement of the bottom and endplate of the third ventricle. Results Early postoperative routine MR scan showed that the hydrocephalus was improved in 7 cases (41.2%)and unchanged in 10 cases(58.8%). While the 3D FIESTA imaging revealed that there were 15 cases (88.2%) in approved group and 2 cases (11.2%) in unchanged group. There were significant differences between routine MR imaging and 3D FIEATS imaging in the early prognostic evaluation of obstructive hydrocephalus (P=0.010). Conclusion Perioperative MR imaging and 3D FIESTA sequence can provide early, objective and accurate imaging guidance for the diagnosis, differential diagnosis and postoperative evaluation of obstructive hydrocephalus.