Porphyra, one of the most important marine crops in Asia, possesses two heteromorphic life phases.Many studies have found that the expressions of the majority of genes of Porphyra are phase-related.However, there is limited knowledge of the regulation expression of these phase-related genes.MicroRNAs (miRNAs) are a class of endogenous small RNAs that play essential regulatory roles in gene expression.To gain an insight into the characteristics and expression patterns of miRNAs and to investigate their roles phase-specific expression phases, we used next generation high-throughput sequencing technology to identify miRNAs of P.haitanensis on a large scale.