Abstract: Titanium capillary is a specially shaped titanium alloy, because its inner diameter is usually less than 1 mm, tube wall thickness is less than 1mm, surface area is so large that they are easily to be polluted and the surface of the capillary of titanium suffers easily from oxidation due to the fever during the process, so in determining capillary oxygen content of titanium, treatment of surface greasy dirt and oxide layer processing is particularly important. HNO3-HF mixed acid, distilled water and acetone were used successively in ultrasonic cleaner to deal with samples, and inert gas fusion-infrared method was used to carry out precision and recovery test. Experimental results are satisfactory.