The invention relates to a low-halogen-content fire-retardant adhesive and a flexible copper clad laminate prepared from the same. The low-halogen-content fire-retardant adhesive comprises synthetic rubber, brominated epoxy resin, biphenyl type epoxy resin, phosphonitrile compounds, an aromatic amine curing agent, an imidazole curing accelerator, inorganic filler, an ion exchanger, an oxidation inhibitor and a solvent. The flexible copper clad laminate prepared from the fire-retardant adhesive comprises a polyimide film, a low-halogen-content fire-retardant adhesive layer and copper foil, wherein the low-halogen-content fire-retardant adhesive layer is coated on the polyimide film, and the copper foil is pressed on the low-halogen-content fire-retardant adhesive layer. The fire-retardant adhesive has low halogen content, excellent flexibility, heat resistance, adhesion property and humidity resistance. The flexible copper clad laminate has excellent flexibility, folding resistance, deflection resistance, dip soldering resistance, ion mobility resistance and high peeling strength, the flame retardance reaches the UL94V-0 grade, and the flexible copper clad laminate is suitable for manufacturing a flexible printed circuit board.