Objective: To investigate the correlation between the retinal vessel density (VD) and the degree of visual field loss in chronic primary angle-closure glaucoma (CPACG). Methods: Eighty-nine CPACG patients (112 eyes)with different degrees of visual field loss were measured with optical coherence tomography angiography (OCTA) for macular VD and para-optic microcirculation VD, and the correlation between them and the degree of visual field defect were analyzed. Results: There was a negative correlation between the VD of the microcirculation in each zone next to the optic disc and the degree of visual field loss (r>–0.728, P<0.05). The receiver operating characteristic (ROC) and area under the curve (AUC) of the total VD of the superficial macula is 0.874. Under the condition of controlling age, intraocular pressure and vision, for every 1% decrease in the total superficial macular VD, the average visual field defect mean deviation (MD) value increases –0.639 dB. Conclusion: The VD of CPACG patients is linearly negatively correlated with visual field defects. OCTA can conveniently and non-invasively observe the blood flow of the fundus in patients with glaucoma. It is found that the retinal VD is reduced before visual field defects, which can be used as a reference index for early diagnosis of CPACG.