To research the value of infrared thermogram in diagnosing ankylosing spondylitis(AS). Analyzed the infrared thermogram images of 131 patients and 100 normal one by using WP-95 medieal infrared thermogram scanner made in China. AS diagnostic standard is consulted by “Rheumatology” edited by JiangMing. AS spine infrared thermogram from cervcotho-racicum to lumbosacral appears to be high temperature red heated area. As wide as the lateral distance between the bilateral saerospinal muscle,the temperature is 1~2.9℃ higher than the bilateral temperature average 1.7℃. Conclusion: Using the infrared thermogram in diagnosing AS has great clinical values.