A green approach has been developed for the synthesis of hydroxypropyl cellulose-g-polytetrahydrofuran (HPC-g-PTHF) graft copolymer via combining living cationic ring-opening polymerization and nucleophile substitution reaction. The living PTHF chains (M-n = 3200 g.mol(-1)) were synthesized in bulk initiated by allyl bromide/AgClO4 without any other hazardous solvents. Then, the living PTHF chains reacted with hydroxyl groups on the HPC backbone with grafting efficiency of ca. 100% to create a series of HPC-g-PTHF graft copolymers with various average grafting numbers (G(N)). The nanosized phase separation micromorphology was dependent on G(N) in HPC-g-PTHF. The water contact angles on graft copolymer film surfaces increased from 61.7 degrees to 87.7 degrees with increasing G(N) from 3 to 10 and after annealing treatment. The silver nanoparticles (AgNPs) in situ formed from AgClO4 uniformly dispersed in graft copolymer matrix and Ag contents were close to the theoretical data based on AgClO4. The HPC-g-PTHF graft copolymer films show good anti-protein adsorption performance against bull serum albumin. The HPC-g-PTHF/AgNPs compounds present good antibacterial activity.