The invention relates to a steel wire open firing, water quenching and thermal insulation combined isothermal quenching device. According to the technical scheme of the invention, the steel wire open firing, water quenching and thermal insulation combined isothermal quenching device is characterized by comprising a water quenching device and a thermal insulation furnace, which are sequentially arranged along the transmission direction of a steel wire, wherein the water quenching device is arranged behind an open-fire furnace, a wire-supporting and splitting brick for supporting the steel wireis arranged at an outlet of the open-fire furnace, and the steel wire enters into the water quenching device via the wire-supporting and splitting brick; and the thermal insulation furnace is arranged behind the water quenching device, and the steel wire getting out of the water quenching device directly enters into the thermal insulation furnace. The water quenching device and the thermal insulation furnace are combined for carrying out isothermal quenching treatment on the steel wire after heating treatment by the open-fire furnace, and the steel wire after the quenching treatment by the device is perfect in transformation of the sorbite structure and good in mechanical properties.