The limitations of oil recovery from carbonate reservoirs are fractures and oil-wet conditions. To overcome the reservoir heterogeneities and reduce fracture transmissibility, preformed particle gel was applied in injector wells. Experimentally, low salinity waterflooding was applied to change the core wettability from oil-wet to water wet for enhanced oil recovery. However, both processes have limitations that cannot be resolved using a single method. A non-uniform fracture width and uniform fracture width models were built using carbonate cores to evaluate the coupling low salinity waterflooding and preformed particle gel in fractured cores and how could be used to improve in-depth water diversion treatment. The results showed that low salinity waterflooding improved in-depth water diversion when injected after PPG directly while seawater showed less effect than low salinity waterflooding. Also, the uniformity of fracture had a significant effect on plugging efficiency oil recovery factor from fractured reservoirs.