Polyacrylonitrile (PAN) precursor nanofiber microyarns were successfully synthesized using a modified electrospinning method, and then were stabilized at different stabilization temperatures. Effects of stabilization temperature on the structure, thermal, and mechanical properties of stabilized microyarns were studied by FTIR, XRD, DSC, TG, and mechanical behavior test. It was found that when the stabilization temperature was above 250 A degrees C, cyclization and dehydrogenation reactions were basically completed, and PAN crystal microstructure was almost completely destroyed, as well as the thermally stable ladder structure was formed. The results also showed that the strength of the stabilized microyarns increased to a threshold value and started to reduce thereafter as the stabilization temperature increased.