One isocyanate group of isophorone diisocyanate trimer was capped with 1,1,2,2-tetrahydro perfluoro-1-decanol. Fluorinated polyurethane containing branched chains (B-FPU) was synthesized by the reaction of different contents of capped trimer, isophorone diisocyanate and perfluoropolyether diol. A solution of B-FPU in xylene and cresol was then prepared and coated on copper wires using high-speed enameled machine to obtain enameled wires. The structures, thermal stability, mechanical properties, and hydrophobic properties of B-FPU were characterized by infrared spectroscopy, thermogravimetric analyzer, universal testing machine and contact angle tester. The breakdown voltage, mechanical properties, thermal properties, and direct solderability of enameled wires were measured by voltage tester, unidirectional scratch tester, softening breakdown tester and solder tester. The effects of capped trimer content on the structure and properties of B-FPU and the corresponding enameled wires were investigated. The results show that the tensile strength and elongation at break of B-FPU with 30% of capped trimer are 30.50 MPa and 952%, respectively. Its initial decomposition temperature and contact angle are increased to 216.6 ℃ and 96.1°, respectively, which are much higher than those of ordinary polyurethane. The breakdown voltage of the corresponding enameled wire is as high as 7033.8 V. The enameled wire prepared using B-FPU with 10% of capped trimer shows the largest breakdown voltage of 7513.4 V, which is 1.6 times of 4719.8 V for ordinary polyurethane enameled wire. At the same time, the mechanical properties, thermal properties, and direct solderability meet the requirements of polyurethane enameled wire.