Abstract: Non-coding small RNAs (ncsRNAs) are endogenous RNA molecule, 20—26 nucleotides in length, which have been found in diverse plants and function as transcriptional and post-transcriptional regulators of gene expression. The microRNAs (miRNAs) and other ncsRNAs play essential roles in development and physiologic process of plants. The miRNAs and other ncsRNAs are conserved among terrestrial plants, and the innovation of miRNAs and other ncsRNAs appears to be associated with the advent of evolution lineages of terrestrial plants, indicating that ncsRNAs have huge impacts on plant phylogeny. This review summarizes the conservation of miRNAs and other ncsRNAs, and their functions in plants. The vital roles of ncsRNAs during the in the evolution of terrestrial plants are also discussed.