The properties of a new type of energetic polyether with side chains containing octa-fluoro pentyl groups are studied. The fluoro-carbonic polyethers are hydroxy-terminated poly (1,1,5-trihydrooctafluoropentylglycidyl ether) (FCPE-1) and its copolyether with tetrahydrofuran (FCPE-2) . The experimental results show that they have higher thermal stability and chemical stability than conventional hydrocarbonic polyethers (HCPE). Moreover, FCPE-1 has better stability property than FCPE-2. The cured polyurathane rubber and the high energy-density propellant of FCPE-2 possess both good mechanical property and excellent stability.