Platinum iridium bonding wire is a high-strength wire bonding material used in the packaging of special microelectronic devices, and heat treatment is the key method for the cold-deformed platinum-iridium alloy microfilament to control the lifetime service performance of the bonding wire. Based on the Φ25 μm Pt-10Ir ultrafine bonding wire, the microstructure and deformation of ultrafine filaments under different annealing processes were analyzed and measured by high-resolution FIB-EBSD linkage characterization technology, and the evolution of their mechanical and electrical properties was statistically studied. The results show that with the increase of annealing temperature, the microstructure gradually changes from fine fibrous grains to partial equiaxed grains. The equiaxed grains preferentially grow at the grain boundary. Simultaneously, the intensity of the silk texture gradually decreases, the breaking force gradually decreases, the elongation gradually increases, and the resistivity shows a trend of first decreasing and then increasing. After the annealing of Pt-10Ir ultra-fine bonding wire at 600°C/30 min, recovery rather than recrystallization occurs in the microstructure, the texture orientation evolves into a deformation texture parallel to the wire drawing direction of <111> with a breaking force of 37.06 cN, a tensile strength of 755.29 MPa, an elongation of 1.30%, and a resistivity of 22.81 μΩ·cm, showing an excellent mechanical/electricity comprehensive performance. This study will provide a theoretical and experimental basis for the optimization of microstructures and properties in high-strength precious metal ultra-fine bonded wire.