Objective To determine the effects of flaxseed on lipid metabolism， fatigue， and inflammation in overweight children.Methods Eighty overweight children ［average age： 11.50 ± 2.11 years； sex： 40 males and 40 females］ were randomly divided into the control （group C， n = 40） and experimental （group W， n = 40） group. A pre-test was carried out after completion of study-related assessments （blood collection； evaluation of the indexes of fatigue， inflammation， stress， and fat metabolism； and completing mental state-related questionnaires and body composition tests）. Participants in group C ate 20 g of expanded wheat （approximately 347 kcal） while those in group W ate 20 g of flaxseed （approximately 420 kcal） every day. Blood samples and body composition tests were carried out on Sunday in weeks 4， 8， 12， and 16 of the intervention. The mental stress questionnaire was completed on Sunday in week 16 of the intervention.Results During the 16-week diet， no significant changes in body mass index （BMI）， body fat rate， triglyceride （TG）， total Cholesterol （TC）， high-density lipoprotein cholesterol （HDL-C）， and low-density lipoprotein cholesterol （LDL-C） were found in group C （P>0.05）. The BMI， body fat rate， TG， TC， and LDL-C of participants tended to trend downward in group W. After week 16， the values of these indexes were significantly lower than those in the pretest and group C at the corresponding time point （P<0.05）. After week 16， the levels of interleukin 6 （IL-6） and tumor necrosis factor α （TNF-α） in group C were higher than those at baseline （P<0.05）. In group W， the levels of IL-6 and TNF- α increased in the first 4 weeks， but decreased continuously thereafter， and were significantly lower than those in the pretest and group C at week 16 （P<0.05）. After 16 weeks of intervention， comprehensive fatigue， physiological fatigue， psychological fatigue， stress， and anxiety in group W were significantly lower than those in group C and the pretest （P<0.05）.Conclusion Long-term consumption of flaxseed by overweight children can reduce the level of inflammatory factors， relieve physical and mental fatigue， regulate lipid metabolism， and improve body composition.