microRNAs are one kind of endogenous no-encoding RNA with about 22 nucleotides in length, and inhibited the translation of mRNAs by partially complementary binding to the 3' UTR of target mRNAs in the post-transcriptional level.  Recent research shows that miRNAs function in the physiological and pathological processes of heart, especially involved in the occurrence and progress of arrhythmias.  Abnormal miRNAs   alters the protein expression of ion channels, causes the cardiac dysfunction, and triggers heart arrhythmias.  The article summarized recent advances about roles of miRNA in arrhythmias and related cardiomyopathy, and discussed the therapeutic potential of miRNAs for heart diseases.