The present invention relates to a method for fine-tuning gene expression levels using a synthetic regulatory sRNA in a prokaryotic cell. The present invention can simultaneously, easily, and quickly apply various target gene combinations to various strains without gene deletion through the synthetic regulatory sRNA for regulating gene expression and is therefore very suitable for measuring the metabolizability of each strain and selecting an optimum strain. In addition, the method has the advantages of easily and quickly selecting a target gene for the inhibition of gene expression and expressing the gene thus selected to a desired degree and thus can be used in producing recombinant strains for the efficient production of various metabolites and establishing a method for the efficient production and is therefore very useful.