Post-transcriptional regulation by RNA binding proteins (RBPs) plays prominent roles in a variety of biological processes. In this study, by analyzing the global regulatory relationship between RBPs and their target mRNAs in yeast, we discovered that most RBP genes are co-regulated with their target genes, but the RBPs tend to dampen expression variation among their target mRNAs. We further examined a well-studied RBP gene, PUF3, and found that the protein decreases the variation of its target mRNAs by differentially affecting their decay. We also constructed a mathematical model to explain the relationship between RBPs and the expression of their target genes. Our results provided new insights into the functional importance of RBPs in coordinating the expression of their target genes.