The invention discloses diffluent side-chain fluorine-containing polyether diol prepared from perfluorinated ethylene oxide and multicomponent cyclic ether through copolymerization. The diffluent side-chain fluorine-containing polyether diol is prepared from perfluoroalkyl substituted ethylene oxide, substituted epoxy propane and oxetane or tetrahydrofuran through copolymerization reaction. The side-chain fluorine-containing copolyether diol with different fluorine contents can be synthesized through changing the raw material proportion; the fluorine raw materials are sufficiently utilized; meanwhile, substituted epoxy propane with different substituent groups can be selected according to the subsequent reaction purposes of the side-chain fluorine-containing polyether diol; the defects of serious phase splitting and processing inconvenience in the organic fluorine compound processing process are overcome; then, the side-chain fluorine-containing polyether diol can be easily dissolved into low-price non-toxicity and low-toxicity solvents in general use in industry; the processing cost can be reduced to a great degree; the processing environment pollution is reduced. Generally, the side-chain fluorine-containing polyether diol provided by the invention is very convenient in various kinds of subsequent use; the use space of the polyether diol is expanded to a great degree.