Abstract: AIM To investigate changes of microRNA expression profiles in rats with selenium deficiency. METHODS Thirty SD rats were randomly divided into a control group, low selenium group, and selenium supplement group, with 10 in each group. Rats in the control group were fed with standard diet, rats in the low selenium group were fed with a low selenium diet, and rats in the selenium supplement group were fed first with a low selenium diet for 14 weeks and then were given sodium selenite for 3 weeks. Seventeen weeks later, blood selenium in all groups was detected. RNA was extracted from myocardial tissue of rats for microRNA microarray detection, identifying differential microRNA of low selenium rats and normal rats. Then, these differential microRNAs were deeply analyzed by GO analysis and were verified through RT-qPCR. RESULTS The model of SD rats with selenium deficiency was successfully constructed (the concentration of selenium was 0.026 ng/L). The levels of blood selenium in the low selenium group decreased significantly compared with those in the control group (P<0.05), but after selenium supplement, they increased significantly (P<0.05). Through microRNA microarray detection, 30 microRNAs with differential expression in the low selenium group were screened. In up-regulated gene expression and the most significant microRNAs were miR-374, miR-16, miR-199a-5p, miR-195 and miR-30e*. In down-regulated gene expression, the most significant microRNAs were miR-3571, miR-675 and miR-450a*. Among these, the expression of miR-374 was the highest, which may be of significant importance in rats with selenium deficiency. CONCLUSION Expressions of miR-374, miR-16, miR-199a-5p, miR-195, miR-30e*, miR-3571, miR-675 and miR-450a* were significnatly abnormal in rats with selenium deficiency, among which miR-374 is most closely related to selenium deficiency, providing an experimental basis for the diagnosis and treatment of Keshan disease with microRNA.