【Objective】 To analyze the characteristics of peripheral blood mononuclear cells (PBMC) collection in healthy children, and explore the factors affecting collection efficiency (CE). 【Methods】 The PBMC data, involving 70 episodes of apheresis from 42 children during January 2017 and June 2020 were retrospectively analyzed All children were collected in Zhujiang Hospital of Southern Medical University. 【Results】 Multiple linear regression analysis showed that mononuclear cells (MNC) in donor collections from healthy children were positively correlated with anticoagulant dosage, lymphocyte count and monocyte count (P<0.05), meanwhile, negatively correlated with age and platelet count. The PBMC CE was negatively correlated with age, platelet count, and processed whole blood volume (P<0.05). CD34⁺ cells (×10⁷ /kg)was negatively correlated with age, meanwhile, positively correlated with numbers of collection and processed whole blood volume(r=-0.79). No statistical differences in red blood cell count, platelet count, lymphocyte count, monocyte count of healthy child donors were notable before versus after apheresis. 【Conclusion】 MNC can be collected effectively in children of different ages. The PBMC collection efficiency was related to age. Meanwhile, the higher the lymphocytes and monocytes were before apheresis, the more MNC were collected. The efficiency of MNC collection would decrease when the apheresis volume of the children exceeded their total blood volume twice. However, the absolute value of CD34+ cells in the final yields would increase.