After the protection of partial hydroxyl groups with trimethylsilyl (TMS) groups, hydroxypropyl cellulose becomes soluble in organic solvents, and the number of hydroxyl groups as initiating groups can be controlled. As a result, a new brushlike graft poly(E-caprolactone) can be prepared with hydroxypropyl cellulose as the backbone polymer by homogeneous ring-opening graft polymerization and deprotection. The protection and deprotection of the TMS group during the entire procedure were carefully monitored with Fourier transform infrared (FTIR) and NMR, and the final graft copolymers were characterized with FTIR, 111 NMR, 13 C NMR, gel permeation chromatography, and differential scanning calorimetry.