Fracturing and packing is a key technology for maintaining and enhancing production in medium-to high-permeability unconsolidated sandstone reservoirs. However, after production begins, the loose cementation of the reservoir, combined with proppant embedment and formation sand invasion, significantly reduces fracture conductivity. Currently, there is a lack of methods to predict fracture conductivity under the combined effects of proppant embedment and formation sand blockage in such reservoirs. A fracturing and packing simulation device was used to conduct composite experiments on proppant embedment and formation sand blockage under closure stresses ranging from 5 MPa to 20 MPa, unconsolidated rock plate samples were used to simulate fracture surfaces. Based on the experimental results, the controlling factors and developed models were analyzed to predict permeability loss due to proppant compaction, fracture width loss caused by embedment, and dynamic permeability changes due to formation sand blockage. The results show that proppant embedment and compaction after fracture closure significantly reduce fracture conductivity, with the main factors being closure stress, reservoir strength, and particle sizes of the proppant and formation sand. Formation sand blockage also exhibits a time-dependent effect, contributing to dynamic conductivity decline. In a typical unconsolidated sandstone reservoir in the Bohai Oilfield, the calculated fracture width loss due to embedment is approximately 19.34%, permeability loss from closure and compaction is about 34.15%, and dynamic permeability loss from formation sand invasion is around 22.89%. The combined effect of these factors results in a total fracture conductivity loss of approximately 59.06%. To prevent excessive blockage, it is recommended that the initial fracture width be maintained at no less than 12.5 mm, large-particle proppants be used, and production rates be controlled during the early production phase. The research results provide important guidance for optimizing fracturing and packing parameters and improving production in unconsolidated sandstone reservoirs.