Objective To explore the value of X-ray, CT and MRI in the diagnosis of early ankylosing spondylitis in patients with sacroiliac joint disorder. Methods The clinical data of 103 patients with sacroiliac joint disorder in early ankylosing spondylitis who had received treatment in our hospital between May 2015 and May 2016 were retrospectively analyzed, which were given X-ray, CT and MRI for examination. The diagnostic values of these three methods were observed and compared. Results The X-ray examination showed that the joint space was widened, CT results showed a narrowing and ambiguous joint space and the MRI examination long T2 and long T1. The detection rate of MRI for the diagnosis of class 0 ankylosing spondylitis was shown to be at 16.50%, higher than that of X-ray and CT, which were both at 0. 00%. The detection rates of MRI and CT were class Ⅰ and class Ⅱ were respectively 31.07% and 32.04%, and 30.10% and 30.10%, both higher than the 7.77% and 15.53%, where the difference was statistically significant (P<0.05, P<0.01). The detection rates of MRI for sclerotin cystic of the articular surface and erosion of articular surface were respectively 85.44% and 96.12%, higher than that of X ray which was 34.95% and 63.11% respectively and than that of CT which was 67.96% and 80.58%, where statistically significant difference was registered (P<0.01). Conclusion For early ankylosing spondylitis in patients with sacroiliac joint disorders, X-ray, CT and MRI are all with certain diagnosis value, among which MRI boasts of higher detection rate in tissue lesions and diagnosis of ankylosing spondylitis, thus it is worthwhile to be utilized in clinical field to make sure early diagnosis and to provide reference for the treatment of this disease.