Objective: To develop a method of retinal microglial cell culture to study the function of the microglial cell in diabetic retinopathy. Methods: Microglia were activated with LPS. Immunocytochemistry, con-focal microscopy, flow cytometry, MTT and ELISA were applied to observe the morphological characters, quantity, and functional changes of the microglia. Results: The purity of the microglia was up to 96% as determined by immunostaining and flow cytometry. Some morphological changes of microglia were observed after treatment with LPS, but their quantity kept stable. Cytokine TNF-? released from microglia increased significantly. Conclusion: The isolated microglial cells are pure by using this culture system, which would provide a valuable tool for studying mechanisms of microglial alterations in diabetic retinopathy.