Objective To evaluate the changes in anterior chamber morphology with the Pentacam three-dimension anterior segment analysis system after YAG laser peripheral iridectomy (LPI) in early primary angle closure glaucoma (PACG) patients in order to investigate the sensitive parameters of the anterior chamber changes. Methods Prospective control study. Forty-seven eyes of 47 PACG patients (acute PACG 21 eyes and chronic PACG 26 eyes) were enrolled in this study.Pentacam examination was performed before and 2 weeks after LPI to measure the central anterior chamber depth (ACD), the anterior chamber volume (ACV) and the peripheral anterior chamber angle (ACA). Statistical analysis included paired t test and independent samples t test. Results ACD increased significantly from (1.84±0.31)mm to (1.89±0.28)mm and ACV increased significantly from (65.04±20.68)mm3 to (92.19±21.07)mm3 after LPI in PACG (t=-3.10, P=0.003; t=-17.02, P=0.000).There was no statistical significance on the changes of ACA [(23.86±5.96)° vs (25.44±6.38)°, t=1.91,P=0.060) after LPI in PACG. The changes of ACV were (29.76±10.84)mm3 in acute PACG and (23.31±10.07)mm3 in chronic PACG. There was statistical significance between two groups (t=2.09, P=0.040).The changes of ACV were (31.93±11.99)mm3 in the patients without medicine and (18.71±7.06)mm3 in the patients with medicine. There was statistical significance between two groups (t=3.17, P=0.005).Conclusion LPI could increase the ACV and deepen the ACD in PACG. ACV and ACD are the sensitive parameters of the anterior chamber changes with Pentacam. The changes of ACV in acute PACG are more significant than that in chronic PACG. The changes of ACV in patients without medicine are more significant than that in patients with medicine.