目的　研究骨盆正位与斜位X线片中骶髂关节的放射解剖学特点，为临床诊断骶髂关节病变提供确切的放射解剖学依据。 方法　在男女各1具成人干燥髂骨和骶骨的耳状面上分别均匀涂上钡粉，合拢骨盆胶带固定，拍摄骨盆正位和斜位X线片；再将钡粉洗净，用细铅丝分别沿着骶骨和髂骨耳状面的边缘环绕，合拢骨盆胶带固定，分别拍摄骨盆正位和斜位X线片。观察耳状面和骶髂关节在骨盆正位片与斜位片上的投影变化和形态特征。  结果　在骨盆正位片可清晰的观察到双侧骶髂关节的前间隙和后间隙及耳状面。斜位片可观察到对侧骶髂关节的情况，骶髂滑膜关节位于X线上骶髂关节间隙的中下2/3；女性骶髂关节较男性短。  结论　骶髂关节在骨盆正位和斜位X线片上有其放射解剖学及性别特征，骶髂关节前间隙和后间隙以及耳状面是观察的重点，骨盆正位X线片基本可满足临床需要。

Objective　To provide the accurate radiological anatomical evidence for clinical diagnosis of lesions of the sacroiliac joints by studying the radiographic anatomic features of the SIJ on the anteroposterior and oblique plain radiography.　Methods　Iliac and sacral auricular surface of each male and female dry adult plevics evenly were coated with barium powder, folded and fastened with the tape and and underwent anteroposterior and oblique plain radiography of the pelvic; then the barium powder was washed away, the edge of the sacral and iliac auricular surfaces were surrounded with thin lead wires, foldedand fastened with tape, and underwent the anterposterior and oblique radiography of the pelvis. the projective changes and morphological characteristics of SIJ and its auricular surface in the anteroposterior and oblique radiography were observed.   Result    The anterior and posterior spaces of sacroiliac spaces and auricular surfaces were clearly displayed in the anteroposterior radiography. the contralateral SIJ could be more clearly displayed in the oblique radiography. The sacroiliac synovial joints were located in the inferior 2/3 of the sacroiliac space.    Conclusions    The radiological anatomic and gender characteristics of SIJ are presented in the anterposterior and oblique radiography of the pelvis. The observation should focus on the anterior and posterior spaces and the scope of auricular surface of SIJ joint. This study indicates that the anteroposterior radiography is enough for meeting the clinical requirement.