The present application relates to a shape memory alloy hypotube as well as use thereof in a blood vessel optical fiber guide wire. The hypotube comprises several spiral coils. This hypotube is made from a shape memory alloy such that its diameter varies over temperature. Thus, it can closely wrap an axial fiber disposed therein. Through phase change properties and shape memory properties of the memory alloy, the inner diameter of the hypotube changes over temperature. The hypotube produces two functions: making a wrapping expand and tight binding fixed. The shape memory alloy hypotube can improve the strength and safety of optical fiber guide wire. The hypotube can easily enter the blood vessel of human body. Further, the conventional winding process can be simplified.
