microRNAs (miRNAs) play important regulatory roles in eukaryotic gene expression, predominantly at the post-transcriptional level. Elaborate and diverse biogenesis pathways have evolved to produce miRNAs. miRNA biogenesis is a multistep process including transcription, precursor slicing, methylation, nuclear export, and RNA-induced silencing complex assembly. In the decade, since the first discovery of plant miRNAs, many enzymes and regulatory proteins involved in miRNA biogenesis in plants have been uncovered and a basic picture of miRNA processing is emerging gradually. In this article, we summarized the current study of plant miRNA biogenesis and discussed the multiple integrated steps and diverse pathways of miRNA processing.