Rod-coil diblock copolymers of PPQ-b-PEG containing poly(phenylquinoline) (PPQ) as the rod block and the poly(ethylene glycol) (PEG) as the coil block were designed and synthesized from Methyl-PEG(M_w:2000), butanedioic anydride 4-Aminoacetophenone, 5-acetyl-2-aminobenzophenone. The structures of PPQ-b-PEG are characterized by IR, ¹HNMR. And thermostabilities are studied.The results show that the first decompostion temperature of PPQ-b-PEG is 250℃.The weight of PPQ-b-PEG is reduced by 5% at 250～400℃. It is reduced rapidly at 400～600 ℃.