Abstract: Objective To explore the combinat ive improvement effects of mult-inutrients on NOS,NO in hippocampus of SD rats exposed lead,and find the better combination of nutrients withantagonism to toxicity of lead.Methods Applying orthogonal design,taking the NOS,NO in hippocampus of rats as indices,7 nutrients were tested on animal experiments.The nutrients were tyrosine,glycine,methionine,taur ine,vitamin C,vitamin B1 and zinc,which were known to have the effects against toxicity of lead and improve lear ning and memory.Results The blood level of lead,activity of NOS and content of NO in hippocampus in the experimental groups supplied nutrients were greater than in control group exposed lead without nutrients(P<0.01).The results of orthogonal design showed that methionine,zinc and vitamin B1 decreased lead level in blood more significantly than other.There were statistic significance of mean difference between groups with those nutrients and without.Zinc increased the content of NO more obviously than other nutr ients.Vitamin B1 couldn.timprove the activity of NOS,increase the content of NO.Mean of groups with vitamin B1 was smaller than one of groups without.There were significance of mean difference.Conclusion There exists synergic effect of mutil-nutrients on improving the activity of NOS,increasing the content of NO in hippocampus of rats exposed lead.The better combination of nutrients is methionine with zinc.