Objective: This study aimed to contrast two different methods to decellularize sheep internal carotid arteries as a tissue-engineered small-diameter vascular scaffold and test histological and physiochemical properties. Methods: Blood vessels were divided into three groups: group A, fresh (control); group B, enzymatic decellularized (experimental I); and group C, enzyme-detergent mixed decellularized (experimental II). Hematoxylin and eosin (HE) staining, elastic and collagenic fiber dyeing, fluorescence staining, and scanning electronic microscopy were performed, and the thickness, tensile strength, burst pressure, moisture content, and DNA content were tested, recorded, and analyzed. Results: Group A revealed blue-stained cell nuclei, while groups B and C showed nuclei removal completely under HE staining and 4', 6-diamidino-2-phenylindole (DAPI) immunofluorescence staining. In group A, the elastic and collagenic fiber staining revealed dense continuous without rupture, while the counterparts in groups B and C were more discontinuous and looser. The cells appeared orderly and compact in group A under a scanning electron microscope, while groups B and C showed only longitudinal fibers in the inner membrane. Group C showed the strongest tensile strength, lowest moisture content, and lowest DNA. Every group resisted pressure over 300 mmHg without burst. Conclusion: The enzyme-detergent mixed decellularization method was milder to damage the blood vessels compared with enzymatic decellularization, and demonstrated a higher level of decellularization and lower level of DNA content. Therefore, it could be used as a better decellularization method for tissue-engineered small-diameter blood vessel.