The soft composite material of polyester film and aramid fiber paper is made by bonding and compounding two sides of aramid fiber paper with polyester film. This product has a heat resistance grade of H, and has good flexibility, excellent mechanical strength, dielectric properties, tear resistance, and paint absorption ability. Suitable for slot to slot insulation of H-level motors and generators, as well as interlayer insulation of dry type transformers. Interval insulation, etc.