The light greenish color of the expressed breast milk is an abnormal phenomenon, which is caused by mastitis due to prolonged milk accumulation. It is necessary to go to the hospital for ultrasound examination, and also for milk culture to see what kind of bacterial infection is caused, and use sensitive antibiotics under the guidance of the doctor to promote recovery. Under normal circumstances, milk is white, but if you are malnourished, your milk may become thin, and the low amount of fat in your milk may cause it to appear light green. During breastfeeding, you need to strengthen the nutrition of your diet, such as drinking more milk and eating more eggs and lean meat, drinking more pork feet and soybean soup and carp soup can promote milk secretion and increase the nutrition of your milk. You need to squeeze out the excess milk after each feeding to avoid mastitis caused by milk accumulation.