To study the effect of multi-micronutrients supplementation on nutritional status of children, 220 students aged 8-12 years were observed for 6 months. A half of them were given the supplements, another half placebo. The results showed that in comparison with the placebo, the supplemented children had a higher urine excretion of vitamin B2 and vitamin C after loading; a higher concentration of serum 25-OH-D3, a high content of hydroxy-proline and hydroxy-proline/creatinine ratio in fast urine, and a higher bone mineral content and bone mass density of the mid-ulna. The supplemented children performed significantly better than the placebo in reading speed, learning capacity and arithmetic examinations. It is concluded that micronutrients supplementation played a notable rule in resulting better nutritional status and learning ability of school children.