A series of cyclic (arylene phosphonate) oligomers were prepared by reaction of phenylphosphonic dichloride(PPD) with various bisphenols under pseudo-high dilution conditions via interfacial polycondensation. The yield of cyclic(arylene phosphonate) oligomers is over 85% by using hexadecyltrimethylammoniun bromide as phase transfer catalyst(PTC) at 0 ℃ . The structures of the cyclic oligomers were confirmed by a combination of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and IR analysis. These cyclic oligomers undergo facile ring-opening polymerization in the melt by using potassium 4

4'-biphenoxide as the initiator to give linear polyphosphonate. Free-radical ring-opening polymerization of cyclic(arylene phosphonate) oligomers containing sulfur linkages was also performed in the melt using 2

2'-dithiobis(benzothiazole) (DTB) as the initiator at 270 ℃ and the resulting polymer had a Mw

of 8 × 103 with a molecular weight distribution of 4. Ring-opening copolymerization of these cyclic oligomers with cyclic carbonate oligomers was also achieved. The average molecular weight of the resulting copolymer is higher than the corresponding homopolymer and the thermal stability of the copolymer is better than the corresponding homopolymer.