Abstract: Objective:To study the effect of n-3 polyunsaturated fattyacids on blood glucose, insulin and blood lipid in rats fed by different diet. Methods:SD rats were randomly divided into 14 groups including the blank control group, sucrose and fat rich control group, three α-linolenic acid groups and three deep-sea fish oil groups fed by normal diet, another three α-linolenic acid groups and three deep-sea fish oil groups fed by sucrose and fat rich diet. The α-linolenic acid groups and the deep-sea fish oil groups were administered respectively with α-linolenic acid and deep-sea fish oil on does of 150, 300, 600mg/kg by gavage. After administered for 8 consecutive weeks, the level of blood glucose, insulin and blood lipid in the rats were determined. Results:α-linolenic acid hadn't any effect on blood glucose, insulin and blood lipid of rats fed by different diet. The level of fasting blood glucose of deep-sea fish oil groups significantly increased (compared with the blank control group, p <0.05) , while the level of insulin of deep-sea fish oil groups significantly decreased (compared with the blank control group, p<0.05) . Deep-sea fish oil hadn't any effect on TG and HDL-C of rats. But deep-sea fish oil could make the level of TC and LDL-C of rats fed by sucrose and fat rich diet decrease, and the level of TC decreased significantly compared with sucrose and fat rich control group.Conclusion:Under the administrated dose of 150 to 600mg/kg, there wasn't any effect of α-linolenic acid on blood glucose, insulin and blood lipid of rats.Deep-sea fish oil could increase the level of fasting blood glucose and decrease the level of insulin in rats, while decreased the level of TC in rats fed by sucrose and fat rich diet.