Taking glass-coated Fe₆₉Co₁₀Si₈B₁₃ alloy microwires as an example, the dependences of sizes, microstructure and mechanical properties of microwires on drawing speed and cooling condition were analyzed, and the tensile fracture mechanism of the microwires under different cooling conditions was discussed. The results show that, with the drawing speed increasing from 5 m· min^-1 to 400 m· min^-1, the diameters of microwires and core-wires decrease from 95.2 μm and 22.7 μm to 14.5 μm and 7.2 μm respectively, and the tensile strength of core-wire increases from 1305 MPa to 5 842 MPa. As the cooling distance is less than 20 mm, the sizes and mechanical properties of microwires decrease drastically with the cooling distance increasing, but the influences of cooling distance on them are not obvious as the distance exceeding 20 mm. As water cooling is applied and the drawing speed exceeds 5 m· min^-1, all the core-wires are amorphous. Applying air cooling, the drawing speed should exceed 20 m· min^-1 to obtain amorphous core-wires. The core-wires exhibit brittle fracture mode accompanied by uneven plastic flow and the brittle tendency increases with the cooling distance increasing.