Poly(aryl ether ether ketone ketone)(PEEKK) is a kind important high-performance polymers due to their excellent thermal stability a nd other outstanding properties similar to PEEK and PEKK.However,the PEEKK’s ins olubility in common solutions and high melt point restrict its processing and ap plications.In this paper,a series of random copolymers composed of poly(aryl eth er ether ketone ketone)(PEEKK)/poly(aryl ether ketone ether ketone ketone) cont a ining bis(o-metheyl) moiety(DM-PEKEKK) were prepared by low temperatur e so lution polycondensation of 4,4′-bis(2,6-dimethylphenoxy)diphenylketone (o -M 2DPOBP),1,4-dipheoxylbenzene(DPB) and terephthaloyl chlorde(TPC) in 1,2 -dichloroethane with the presence of AlCl 3 and DMF. The copolymers were chara cterized by FT-IR,DSC,WAXD,TGA,etc.The results show that glass transitio n te mperature increases greatly with the increasing of the ratio of o-M 2DPOBP /DPB,while melting temperature and crystallinity of copolymers decrease.The solu bility of the copolymers is improved greatly,while the copolymers still exhibit excellent thermostability.