Increased tissue n-3 polyunsaturated fatty acid (PUFA) is associated with improved insulin sensitivity in type 2 diabetes. However, this relationship among Chinese is not clear. To investigate the relationship between plasma phospholipids (PL) fatty acid composition and insulin resistance (IR) in type 2 diabetes mellitus, 186 type 2 diabetes and 180 healthy subjects were studied in this case-control study. In the sex, age and BMI controlled partial correlation, homeostasis model assessment (HOMA)-IR and blood glucose was significantly negatively correlated with plasma PL n-3 PUFA, 20:5n-3 and ratio of n-3:n-6 (p<0.01), and positively correlated with n-6 PUFA (p<0.001) and saturated fatty acid (p<0.05) in the diabetes patients. PL 22:6n-3 was also significantly negatively correlated with HOMA-IR (p<0.01), but not with blood glucose. Fasting insulin was significantly negatively correlated with plasma PL n-3 PUFA, 20:5n-3, 22:6n-3 and ratio of n-3:n-6 (p<0.01). The 18:3n-3 was not associated with HOMA-IR and fasting insulin. The results suggested that increased plasma PL n-3 PUFA, 20:5n-3, 22:6n-3 and ratio of n-3:n-6 PUFA was associated with decreased HOMA-IR in type 2 diabetes. Increased plasma PL n-3 PUFA improves insulin sensitivity in type 2 diabetes.