We aimed to investigate the trends of breast milk lutein concentrations at different times and their relationship with dietary lutein intake during the 12 weeks after delivery. Breast milk samples were collected from 37 mothers at 4, 8, and 12 weeks postpartum. A HPLC detection method was used to measure breast milk lutein concentrations. Dietary intake was assessed using a food frequency questionnaire (FFQ), and then dietary lutein intake was calculated. The correlations between dietary lutein intake and breast milk lutein concentrations during lactation were investigated by Pearson’s correlation coefficient. General linear regression models were used to evaluate the optimal regression equation. The mean values of dietary lutein intake at 4, 8, and 12 weeks postpartum were 5.22 ± 3.60, 7.28 ± 4.30, and 7.33 ± 4.24 (mg/d), respectively. The mean values of breast milk lutein concentrations at 4, 8, and 12 weeks postpartum were as follows: 46.41 ± 41.36, 57.96 ± 40.00, and 62.33 ± 30.10 (μg/L), respectively. Breast milk lutein concentrations were positively associated with dietary lutein intake at 4 weeks postpartum (r = 0.527, P < 0.05), which was consistent with the positive correlations observed at 8 and 12 weeks postpartum (r = 0.444, P < 0.05; r = 0.468, P < 0.05) by the sensitivity analysis. Increased dietary lutein intake can increase the concentration of lutein in the breast milk, and women are recommended to increase their dietary intake of green leafy vegetables and fruits that are rich in lutein during the pregnancy and postpartum periods.