Temperature of molten PEBAX resin is controlled in the extrusion process to fabricate the outer tube of a medical micro guidewire. The temperature control system consists of band heaters, temperature sensors, solid state relays (SSR), and multi-channel temperature controller. The heaters and sensors are installed onto a specially designed mold part and resin-feeding parts. The temperatures of the mold and feeders are separately controlled to guarantee quality of the produced outer tube of the micro guidewires.