Adsorption layer nanoreactor synthesis (ALRS) and in situ polymerization were coupled to fabricate polyurethane (PU) hybrid membranes including Ag/multiwalled carbon nanotube (Ag/MWCNT) composite nanomaterials for high separation performance. Ag nanoparticles were initially generated on the MWCNT surface via ALRS. PU membranes that contain Ag-MWCNTs were then prepared using in situ polymerization. Precipitation coupled with in situ polymerization was also employed to prepare reference Ag-MWCNT/PU hybrid membranes. Transmission electron microscopy, UV-vis spectrophotometry, X-ray diffraction, Raman spectroscopy, and thermogravimetric analysis were used to characterize the difference in the morphologies of Ag-MWCNTs by the two preparation methods. Differential scanning calorimetry and scanning electron microscopy were applied to analyze the morphology and thermal stability of hybrid membranes. Swelling-sorption and pervaporation experiments were carried out to evaluate the separation performance of different hybrid membranes. The results demonstrate that Ag nanoparticles generated by ALRS have a smaller size and better distribution than those prepared by the precipitation method. The PU hybrid membrane that contains Ag-MWCNTs via ALRS shows a higher separation performance than the PU membrane containing Ag-MWCNTs prepared by the precipitation method, and the reference MWCNT/PU membrane. This outcome is due to the synergy effect of small Ag particles and MWCNTs on benzene molecules. An increase in the AgNO3 content causes an increased formation of Ag particles on the MWCNT surface, which enhanced the separation performance of the hybrid membranes. When excess AgNO3 was added (>15.2 g.L-1), numerous large Ag particles and Ag aggregates formed in the hybrid membranes, which reduced the separation performance of hybrid membranes.