Aiming at the requirement of high precision positioning for the feed through of infrared detector,a low temperature brazed feed through is designed,and the fabrication technology of the feed through is studied in this paper.AuSn solder with high strength and low melting point is selected,metal parts and ceramic parts of feed through are welded below 350°C.By studying the effect of brazing temperature and holding time on weld quality and leakage rate,high precision feed through with high air tightness are successfully fabricated.