Comb-shaped graft copolymers with poly(methyl methacrylate) as a handle were synthesized by the macromonomer technique in two steps. First, polytetrahydrofuran acrylate (A-PTHF), prepared by the living cationic ring-opening polymerization of tetrahydrofuran, underwent homopolymerization with 1-(ethoxycarbonyl)prop-1-yl dithiobenzoate as an initiator under Co-60 gamma irradiation at room temperature; Second, the handle of the comb-shaped copolymers was prepared by the block copolymerization of methyl methacrylate with P(A-PTHF) as a macroinitiator under Co-60 gamma irradiation. The two-step polymerizations were proved to be controlled with the following evidence: the straight line of ln[M](0)/[M] versus the polymerization time, the linear increase in the number-average molecular weight with the conversion, and the relatively narrow molecular weight distribution. The structures of the P(A-PTHF) and final comb-shaped copolymers were characterized by H-1 NMR spectroscopy and gel permeation chromatography.