As the development of deep fractured reservoirs，water channeling has become increasingly prominent，leading to the wastage of formation energy and a decrease in oil recovery efficiency. The primary cause of water channeling in these complex fracture networks is extreme heterogeneity. Urgent measures are required to plug these water breakthrough channels，with plugging agents playing a central role in addressing this challenge. Deep fractured reservoirs are characterized by high temperatures（≥ 110 ℃）and high salinity（≥20×10⁴ mg/L）. Under these conditions，conventional gels struggle to maintain stability. To overcome these challenges，modified nano-silica was synthesized by introducing hydroxyl and phenolic hydroxyl groups into nano-silica through diazotization and oxidation reactions using 3-amino-4-hydroxybenzenesulfonic acid. This modified nano-silica was then reacted with nonionic polymer，hexamethylenetetramine（HMTA），and hydroquinone to produce a nano-hybrid gel. The formula of nano-hybrid gel was optimized based on gelation performance and dehydration rate. The stability，viscoelasticity and blocking capability of nano-hybrid gel were evaluated. A temperature and pressure-resistant visualized fracture network model was established according to the geological model of typical deep fractured reservoirs in Northwest oilfield. The residual oil distribution patterns were analyzed，and then the multi-round blocking effectiveness was determined. The results showed that the nano-hybrid gel with formula of 0.8% nonionic polymer，0.2% modified nano-silica，0.4% HMTA and 0.4% hydroquinone could remain stable for up to 60 days at temperatures ≤140 ℃ with a dehydration rate <10% . Modified nano-silica significantly enhanced the viscoelastic properties of nano-hybrid gel. The nano-hybrid gel exhibited excellent blocking effects on single fractures with various scales （1—10 mm）. Under the condition of 140 ℃，2 MPa backpressure and 22 × 10⁴ mg/L salinity，multi-round blocking experiments with nano-hybrid gel increased the recovery efficiency of fracture network model by 15.9 percentage points. The nano-hybrid gel demonstrated superior thermal and salt resistance，viscoelasticity and long-term stability，which made it well-suited for effective plugging and enhanced oil recovery in deep fractured reservoirs.