AIM: To observe the anterior segment difference between primary angle-closure glaucoma(PACG) and normal eyes. METHODS:With the use of anterior segment optical coherence tomography(AS-OCT), we observed 116 PACG patients and 336 normal people for the anterior segment structures, including lens thickness(LT), anterior chamber depth(ACD) and angle opening distance(AOD). RESULTS:Compared with normal eyes, PACG eyes had shallower ACD, thicker LT and shorter AOD(P<0.05). CONCLUSION:PACG is charactered with shallower ACD, thicker LT and shorter AOD. AOD could be a diagnosing character for the early stage of PACG. AS-OCT is a useful tool for the early diagnosis of PACG.